/* ============================================================
   STUDENT GPT PRO — Premium Design System
   Linear.app dark theme meets Stripe quality
   ============================================================ */

/* ── CSS Custom Properties ────────────────────────────────── */
:root {
  /* Canvas & Surface */
  --bg-canvas: #0a0a0f;
  --bg-surface: #111118;
  --bg-elevated: #1a1a24;
  --bg-hover: #222233;
  --bg-active: #2a2a3d;

  /* Borders */
  --border-subtle: rgba(255, 255, 255, 0.06);
  --border-default: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.12);
  --border-focus: rgba(124, 58, 237, 0.5);

  /* Text */
  --text-primary: #f0f0f5;
  --text-secondary: #a0a0b5;
  --text-muted: #606075;
  --text-inverse: #0a0a0f;

  /* Accent */
  --accent-primary: #7c3aed;
  --accent-secondary: #2563eb;
  --accent-gradient: linear-gradient(135deg, #7c3aed, #2563eb);
  --accent-gradient-hover: linear-gradient(135deg, #8b5cf6, #3b82f6);
  --accent-glow: 0 0 20px rgba(124, 58, 237, 0.3);
  --accent-glow-strong: 0 0 40px rgba(124, 58, 237, 0.4);

  /* Semantic */
  --color-success: #10b981;
  --color-success-bg: rgba(16, 185, 129, 0.1);
  --color-error: #ef4444;
  --color-error-bg: rgba(239, 68, 68, 0.1);
  --color-warning: #f59e0b;
  --color-warning-bg: rgba(245, 158, 11, 0.1);

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.6);
  --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.3), 0 0 0 1px var(--border-subtle);
  --shadow-card-hover: 0 8px 32px rgba(0, 0, 0, 0.5), 0 0 0 1px var(--border-default);
  --shadow-glow-purple: 0 0 30px rgba(124, 58, 237, 0.15);
  --shadow-glow-blue: 0 0 30px rgba(37, 99, 235, 0.15);

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 20px;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.2s ease;
  --transition-slow: 0.3s ease;
  --transition-spring: 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);

  /* Spacing */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  /* Z-index */
  --z-sidebar: 100;
  --z-bottom-nav: 100;
  --z-slide-menu: 200;
  --z-modal: 300;
  --z-toast: 400;
  --z-loading: 500;

  /* Layout */
  --sidebar-width: 260px;
  --sidebar-collapsed: 72px;
  --bottom-nav-height: 64px;
  --header-height: 64px;
}

/* ── Reset & Base ─────────────────────────────────────────── */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-weight: 400;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-canvas);
  min-height: 100vh;
  overflow-x: hidden;
}

a {
  color: var(--accent-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--accent-gradient-hover);
}

img {
  max-width: 100%;
  display: block;
}

::selection {
  background: rgba(124, 58, 237, 0.3);
  color: var(--text-primary);
}

::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.1);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.18);
}

/* ── Typography ───────────────────────────────────────────── */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

h1 {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

h2 {
  font-size: 1.875rem;
  font-weight: 700;
  letter-spacing: -0.025em;
}

h3 {
  font-size: 1.375rem;
}

h4 {
  font-size: 1.125rem;
  font-weight: 600;
}

h5 {
  font-size: 1rem;
  font-weight: 500;
}

h6 {
  font-size: 0.875rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

p {
  color: var(--text-secondary);
  line-height: 1.7;
}

.text-gradient {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.text-muted { color: var(--text-muted); }
.text-secondary { color: var(--text-secondary); }
.text-primary { color: var(--text-primary); }
.text-success { color: var(--color-success); }
.text-error { color: var(--color-error); }
.text-warning { color: var(--color-warning); }

/* ── Buttons ──────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: 10px 20px;
  font-family: var(--font-sans);
  font-size: 0.875rem;
  font-weight: 500;
  line-height: 1.5;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
  white-space: nowrap;
  user-select: none;
  outline: none;
  position: relative;
  overflow: hidden;
}

.btn:focus-visible {
  box-shadow: 0 0 0 2px var(--bg-canvas), 0 0 0 4px var(--accent-primary);
}

.btn:active {
  transform: scale(0.98);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

.btn-primary {
  background: var(--accent-gradient);
  color: white;
  border: none;
  box-shadow: 0 2px 8px rgba(124, 58, 237, 0.3);
}

.btn-primary:hover {
  background: var(--accent-gradient-hover);
  box-shadow: 0 4px 16px rgba(124, 58, 237, 0.4);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0) scale(0.98);
}

.btn-secondary {
  background: var(--bg-elevated);
  color: var(--text-primary);
  border: 1px solid var(--border-default);
}

.btn-secondary:hover {
  background: var(--bg-hover);
  border-color: var(--border-strong);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: none;
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-primary);
}

.btn-danger {
  background: rgba(239, 68, 68, 0.12);
  color: var(--color-error);
  border: 1px solid rgba(239, 68, 68, 0.2);
}

.btn-danger:hover {
  background: rgba(239, 68, 68, 0.2);
  border-color: rgba(239, 68, 68, 0.3);
}

.btn-block {
  width: 100%;
}

.btn-sm {
  padding: 6px 14px;
  font-size: 0.8125rem;
  border-radius: var(--radius-sm);
}

.btn-lg {
  padding: 14px 28px;
  font-size: 1rem;
  border-radius: var(--radius-md);
}

/* ── Cards ────────────────────────────────────────────────── */
.card {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: all var(--transition-base);
  position: relative;
}

.card:hover {
  border-color: var(--border-default);
  box-shadow: var(--shadow-card-hover);
}

.feature-card {
  background: rgba(255, 255, 255, 0.03);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(124, 58, 237, 0.3), transparent);
  opacity: 0;
  transition: opacity var(--transition-base);
}

.feature-card:hover {
  transform: translateY(-2px);
  border-color: var(--border-default);
  box-shadow: var(--shadow-card-hover), var(--shadow-glow-purple);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-card-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  background: rgba(124, 58, 237, 0.1);
  color: var(--accent-primary);
  font-size: 1.25rem;
  margin-bottom: var(--space-4);
}

.feature-card h3 {
  margin-bottom: var(--space-2);
  font-size: 1.125rem;
}

.feature-card p {
  font-size: 0.9375rem;
  line-height: 1.6;
}

/* Stat Cards */
.stat-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  position: relative;
  overflow: hidden;
  transition: all var(--transition-base);
}

.stat-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-gradient);
  opacity: 0.6;
}

.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-card-hover);
}

.stat-card-label {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-2);
}

.stat-card-value {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  line-height: 1;
}

.stat-card-change {
  font-size: 0.8125rem;
  font-weight: 500;
  margin-top: var(--space-2);
}

.stat-card-change.positive {
  color: var(--color-success);
}

.stat-card-change.negative {
  color: var(--color-error);
}

/* Module Cards */
.module-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  cursor: pointer;
  transition: all var(--transition-base);
  position: relative;
}

.module-card:hover {
  transform: translateY(-2px);
  border-color: var(--border-default);
  box-shadow: var(--shadow-card-hover), var(--shadow-glow-purple);
}

.module-card-icon {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  background: rgba(124, 58, 237, 0.1);
  color: var(--accent-primary);
  font-size: 1.25rem;
  margin-bottom: var(--space-4);
  transition: all var(--transition-base);
}

.module-card:hover .module-card-icon {
  background: rgba(124, 58, 237, 0.18);
}

.module-card-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--space-1);
}

.module-card-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.module-card-meta {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  margin-top: var(--space-4);
  font-size: 0.8125rem;
  color: var(--text-muted);
}

/* Session List */
.session-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.session-item:hover {
  background: rgba(255, 255, 255, 0.04);
}

.session-item.active {
  background: rgba(124, 58, 237, 0.08);
}

.session-item-title {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-primary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.session-item-meta {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Testimonial Card */
.testimonial-card {
  background: rgba(255, 255, 255, 0.03);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  position: relative;
}

.testimonial-card-quote {
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: var(--space-6);
  font-style: italic;
}

.testimonial-card-author {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.testimonial-card-avatar {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.875rem;
  color: white;
}

.testimonial-card-name {
  font-size: 0.9375rem;
  font-weight: 600;
}

.testimonial-card-role {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

/* Pricing Cards */
.pricing-card {
  background: rgba(255, 255, 255, 0.03);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: var(--space-10);
  transition: all var(--transition-base);
  position: relative;
}

.pricing-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.pricing-card.featured {
  background: rgba(124, 58, 237, 0.06);
  border-color: rgba(124, 58, 237, 0.2);
  box-shadow: var(--shadow-glow-purple);
  position: relative;
}

.pricing-card.featured::before {
  content: '';
  position: absolute;
  inset: -1px;
  border-radius: inherit;
  padding: 1px;
  background: var(--accent-gradient);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  animation: borderGlow 3s ease-in-out infinite;
}

@keyframes borderGlow {
  0%, 100% { opacity: 0.6; }
  50% { opacity: 1; }
}

.pricing-card-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 4px 12px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-radius: var(--radius-full);
  background: var(--accent-gradient);
  color: white;
  margin-bottom: var(--space-4);
}

.pricing-card-name {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--space-2);
}

.pricing-card-desc {
  font-size: 0.9375rem;
  color: var(--text-muted);
  margin-bottom: var(--space-6);
}

.pricing-card-price {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
  margin-bottom: var(--space-6);
}

.pricing-card-price .currency {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.pricing-card-price .amount {
  font-size: 3.5rem;
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1;
}

.pricing-card-price .period {
  font-size: 0.9375rem;
  color: var(--text-muted);
}

.pricing-card-features {
  list-style: none;
  margin-bottom: var(--space-8);
}

.pricing-card-features li {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-2) 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.pricing-card-features li::before {
  content: '✓';
  color: var(--color-success);
  font-weight: 700;
  font-size: 0.875rem;
}

/* ── Forms ────────────────────────────────────────────────── */
.form-group {
  margin-bottom: var(--space-5);
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: var(--space-2);
}

.form-input,
.form-select {
  width: 100%;
  padding: 10px 14px;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  color: var(--text-primary);
  background: var(--bg-surface);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  outline: none;
  transition: all var(--transition-base);
  appearance: none;
  -webkit-appearance: none;
}

.form-input::placeholder,
.form-select::placeholder {
  color: var(--text-muted);
}

.form-input:hover,
.form-select:hover {
  border-color: var(--border-strong);
}

.form-input:focus,
.form-select:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(124, 58, 237, 0.15);
}

.form-input.error {
  border-color: var(--color-error);
  box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.1);
}

.form-error {
  font-size: 0.8125rem;
  color: var(--color-error);
  margin-top: var(--space-1);
}

.form-hint {
  font-size: 0.8125rem;
  color: var(--text-muted);
  margin-top: var(--space-1);
}

.form-select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23606075' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
}

textarea.form-input {
  min-height: 100px;
  resize: vertical;
  line-height: 1.6;
}

/* ── Badges ───────────────────────────────────────────────── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 10px;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.badge-free {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-secondary);
}

.badge-pro {
  background: rgba(124, 58, 237, 0.15);
  color: #a78bfa;
}

.badge-premium {
  background: var(--accent-gradient);
  color: white;
}

/* ── Landing Page ─────────────────────────────────────────── */
.landing-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  padding: var(--space-4) var(--space-8);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(10, 10, 15, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-subtle);
  transition: all var(--transition-slow);
}

.landing-nav.scrolled {
  background: rgba(10, 10, 15, 0.95);
  box-shadow: var(--shadow-md);
}

.landing-nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.landing-nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  list-style: none;
}

.landing-nav-links a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.landing-nav-links a:hover {
  color: var(--text-primary);
}

.landing-nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* Hero Section */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--header-height) + var(--space-16)) var(--space-8) var(--space-16);
  overflow: hidden;
}

.hero-orb {
  position: absolute;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(124, 58, 237, 0.15) 0%, rgba(37, 99, 235, 0.08) 40%, transparent 70%);
  filter: blur(80px);
  pointer-events: none;
  animation: orbFloat 8s ease-in-out infinite;
}

@keyframes orbFloat {
  0%, 100% { transform: translate(0, 0) scale(1); }
  25% { transform: translate(30px, -20px) scale(1.05); }
  50% { transform: translate(-20px, 30px) scale(0.95); }
  75% { transform: translate(20px, 20px) scale(1.02); }
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: 6px 16px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: rgba(124, 58, 237, 0.1);
  border: 1px solid rgba(124, 58, 237, 0.2);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-6);
  position: relative;
  z-index: 1;
}

.hero-badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-success);
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.8); }
}

.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.1;
  margin-bottom: var(--space-6);
  position: relative;
  z-index: 1;
  max-width: 800px;
}

.hero-subtitle {
  font-size: clamp(1.0625rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto var(--space-8);
  line-height: 1.7;
  position: relative;
  z-index: 1;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  position: relative;
  z-index: 1;
}

.hero-stats {
  display: flex;
  align-items: center;
  gap: var(--space-12);
  margin-top: var(--space-16);
  position: relative;
  z-index: 1;
}

.hero-stat {
  text-align: center;
}

.hero-stat-value {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-stat-label {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: var(--space-1);
}

/* Features Section */
.features-section {
  padding: var(--space-16) var(--space-8);
  max-width: 1200px;
  margin: 0 auto;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-12);
}

.section-header h2 {
  font-size: 2.25rem;
  margin-bottom: var(--space-3);
}

.section-header p {
  font-size: 1.125rem;
  color: var(--text-muted);
  max-width: 540px;
  margin: 0 auto;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-6);
}

/* CTA Section */
.cta-section {
  padding: var(--space-16) var(--space-8);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.cta-section::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 0%, rgba(124, 58, 237, 0.05) 50%, transparent 100%);
  pointer-events: none;
}

.cta-section h2 {
  font-size: 2.5rem;
  margin-bottom: var(--space-4);
}

.cta-section p {
  font-size: 1.125rem;
  color: var(--text-muted);
  margin-bottom: var(--space-8);
}

/* Pricing Section */
.pricing-section {
  padding: var(--space-16) var(--space-8);
  max-width: 1100px;
  margin: 0 auto;
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-6);
  align-items: start;
}

/* Testimonials Section */
.testimonials-section {
  padding: var(--space-16) var(--space-8);
  max-width: 1200px;
  margin: 0 auto;
}

.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: var(--space-6);
}

/* ── Auth Pages ───────────────────────────────────────────── */
.auth-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-8);
  position: relative;
}

.auth-page::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 500px;
  height: 500px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(124, 58, 237, 0.08) 0%, transparent 70%);
  filter: blur(60px);
  pointer-events: none;
}

.auth-card {
  width: 100%;
  max-width: 420px;
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: var(--space-10);
  position: relative;
  z-index: 1;
  box-shadow: var(--shadow-xl);
  animation: fadeInUp 0.5s ease;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.auth-logo {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  font-size: 1.375rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-8);
  letter-spacing: -0.02em;
}

.auth-title {
  font-size: 1.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: var(--space-2);
}

.auth-subtitle {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9375rem;
  margin-bottom: var(--space-8);
}

.auth-footer {
  text-align: center;
  margin-top: var(--space-6);
  font-size: 0.9375rem;
  color: var(--text-muted);
}

.auth-footer a {
  color: var(--accent-primary);
  font-weight: 500;
}

.auth-divider {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  margin: var(--space-6) 0;
  color: var(--text-muted);
  font-size: 0.8125rem;
}

.auth-divider::before,
.auth-divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border-subtle);
}

/* ── Dashboard ────────────────────────────────────────────── */
.dashboard-welcome {
  margin-bottom: var(--space-8);
}

.dashboard-welcome h1 {
  font-size: 1.75rem;
  margin-bottom: var(--space-1);
}

.dashboard-welcome p {
  color: var(--text-muted);
}

.dashboard-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-4);
  margin-bottom: var(--space-8);
}

.dashboard-section-title {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-4);
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.dashboard-modules {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-4);
  margin-bottom: var(--space-8);
}

/* ── Sidebar ──────────────────────────────────────────────── */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--sidebar-width);
  background: var(--bg-surface);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-right: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  z-index: var(--z-sidebar);
  transition: transform var(--transition-slow);
  overflow: hidden;
}

.sidebar-header {
  padding: var(--space-5) var(--space-5);
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-subtle);
  min-height: var(--header-height);
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.sidebar-nav {
  flex: 1;
  padding: var(--space-3);
  overflow-y: auto;
  overflow-x: hidden;
}

.sidebar-nav-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  margin-bottom: 2px;
}

.sidebar-nav-item:hover {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-primary);
}

.sidebar-nav-item.active {
  background: rgba(124, 58, 237, 0.1);
  color: var(--text-primary);
  box-shadow: inset 0 0 0 1px rgba(124, 58, 237, 0.2);
}

.sidebar-nav-item.active::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 3px;
  height: 20px;
  border-radius: 0 3px 3px 0;
  background: var(--accent-primary);
}

.sidebar-nav-icon {
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.sidebar-section-label {
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  padding: var(--space-4) var(--space-3) var(--space-2);
}

.sidebar-footer {

/* ── Dashboard Layout ────────────────────────────────────── */
.dashboard-welcome {
  padding: var(--space-8) var(--space-8) var(--space-4);
}

.dashboard-section-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
  letter-spacing: -0.01em;
}

  padding: var(--space-4);
  border-top: 1px solid var(--border-subtle);
}

.sidebar-user {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background var(--transition-fast);
}

.sidebar-user:hover {
  background: rgba(255, 255, 255, 0.04);
}

.sidebar-user-avatar {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.875rem;
  color: white;
  flex-shrink: 0;
}

.sidebar-user-info {
  flex: 1;
  min-width: 0;
}

.sidebar-user-name {
  font-size: 0.875rem;
  font-weight: 600;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.sidebar-user-email {
  font-size: 0.75rem;
  color: var(--text-muted);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* ── Bottom Nav (Mobile) ──────────────────────────────────── */

/* ── Page Layout with Sidebar ────────────────────────────── */
.page-with-sidebar {
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  padding-bottom: var(--space-8);
}

@media (max-width: 1024px) {
  .page-with-sidebar {
    margin-left: 0;
    padding-bottom: calc(var(--bottom-nav-height) + var(--space-6));
  }
}

.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: var(--bottom-nav-height);
  background: rgba(17, 17, 24, 0.95);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-around;
  z-index: var(--z-bottom-nav);
  padding-bottom: env(safe-area-inset-bottom, 0);
}

.bottom-nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: var(--space-2);
  font-size: 0.6875rem;
  font-weight: 500;
  color: var(--text-muted);
  text-decoration: none;
  transition: color var(--transition-fast);
  position: relative;
  min-width: 56px;
}

.bottom-nav-item:hover {
  color: var(--text-secondary);
}

.bottom-nav-item.active {
  color: var(--accent-primary);
}

.bottom-nav-item.active::before {
  content: '';
  position: absolute;
  top: -1px;
  left: 50%;
  transform: translateX(-50%);
  width: 24px;
  height: 2px;
  border-radius: 1px;
  background: var(--accent-primary);
  box-shadow: 0 0 8px rgba(124, 58, 237, 0.5);
}

.bottom-nav-icon {
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.125rem;
}

/* ── Hamburger / Slide Menu ───────────────────────────────── */
.hamburger-btn {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: transparent;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
  border-radius: var(--radius-md);
  transition: background var(--transition-fast);
}

.hamburger-btn:hover {
  background: rgba(255, 255, 255, 0.06);
}

.hamburger-line {
  width: 18px;
  height: 2px;
  background: currentColor;
  border-radius: 1px;
  transition: all var(--transition-base);
  position: relative;
}

.hamburger-line::before,
.hamburger-line::after {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background: currentColor;
  border-radius: 1px;
  transition: all var(--transition-base);
}

.hamburger-line::before { top: -6px; }
.hamburger-line::after { bottom: -6px; }

.hamburger-btn.active .hamburger-line {
  background: transparent;
}

.hamburger-btn.active .hamburger-line::before {
  top: 0;
  transform: rotate(45deg);
}

.hamburger-btn.active .hamburger-line::after {
  bottom: 0;
  transform: rotate(-45deg);
}

.slide-menu {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--sidebar-width);
  background: var(--bg-surface);
  border-right: 1px solid var(--border-subtle);
  z-index: var(--z-slide-menu);
  transform: translateX(-100%);
  transition: transform var(--transition-slow);
  box-shadow: var(--shadow-xl);
}

.slide-menu.open {
  transform: translateX(0);
}

.slide-menu-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  z-index: calc(var(--z-slide-menu) - 1);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-slow);
}

.slide-menu-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

/* ── Chat Interface ───────────────────────────────────────── */
/* ── Chat Page Layout ────────────────────────────────────── */
.chat-page {
  display: flex;
  flex-direction: column;
  height: 100vh;
  margin-left: var(--sidebar-width);
  background: var(--bg-canvas);
  position: relative;
}

@media (max-width: 1024px) {
  .chat-page {
    margin-left: 0;
  }
}

.chat-header {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-5);
  border-bottom: 1px solid var(--border-subtle);
  background: rgba(10, 10, 15, 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  min-height: var(--header-height);
}

.chat-header-title {
  font-size: 1rem;
  font-weight: 600;
}

.chat-header-subtitle {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-6) var(--space-8);
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
  scroll-behavior: smooth;
}

.message {
  display: flex;
  gap: var(--space-3);
  max-width: 720px;
  animation: messageIn 0.3s ease;
  width: 100%;
}

@keyframes messageIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.message-user {
  flex-direction: row-reverse;
  margin-left: auto;
}

.message-avatar {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 600;
  flex-shrink: 0;
  margin-top: 2px;
}

.message-ai .message-avatar {
  background: var(--accent-gradient);
  color: white;
}

.message-user .message-avatar {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-secondary);
}

.message-bubble {
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-lg);
  font-size: 0.9375rem;
  line-height: 1.65;
  max-width: 100%;
  word-break: break-word;
}

.message-ai .message-bubble {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-top-left-radius: var(--radius-sm);
  color: var(--text-primary);
}

.message-user .message-bubble {
  background: rgba(124, 58, 237, 0.15);
  border: 1px solid rgba(124, 58, 237, 0.2);
  border-top-right-radius: var(--radius-sm);
  color: var(--text-primary);
}

.message-bubble p {
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.message-bubble p:last-child {
  margin-bottom: 0;
}

.message-bubble code {
  background: rgba(255, 255, 255, 0.06);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.875em;
}

.message-bubble pre {
  background: var(--bg-canvas);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  overflow-x: auto;
  margin: var(--space-3) 0;
}

.message-bubble pre code {
  background: none;
  padding: 0;
  font-size: 0.875rem;
  line-height: 1.6;
}

/* Typing Indicator */
.typing-indicator {
  display: flex;
  gap: 4px;
  align-items: center;
  padding: var(--space-3) var(--space-4);
}

.typing-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--text-muted);
  animation: typingPulse 1.4s ease-in-out infinite;
}

.typing-dot:nth-child(2) { animation-delay: 0.2s; }
.typing-dot:nth-child(3) { animation-delay: 0.4s; }

@keyframes typingPulse {
  0%, 60%, 100% {
    opacity: 0.3;
    transform: scale(0.85);
  }
  30% {
    opacity: 1;
    transform: scale(1);
  }
}

/* Chat Input Area */
/* ── Chat Input Area ─────────────────────────────────────── */
.chat-input-area {
  padding: var(--space-3) var(--space-5) var(--space-4);
  background: var(--bg-canvas);
  border-top: 1px solid var(--border-subtle);
  position: relative;
  z-index: 1;
}


/* ── Chat Input Row ──────────────────────────────────────── */
.chat-input-row {
  display: flex;
  align-items: flex-end;
  gap: var(--space-3);
  max-width: 720px;
  margin: 0 auto;
  background: var(--bg-elevated);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-lg);
  padding: var(--space-2) var(--space-3);
  transition: border-color var(--transition-base), box-shadow var(--transition-base);
}

.chat-input-row:focus-within {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(124, 58, 237, 0.12);
}

.chat-input-wrapper {
  display: flex;
  align-items: flex-end;
  gap: var(--space-3);
  max-width: 720px;
  margin: 0 auto;
  background: var(--bg-elevated);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-lg);
  padding: var(--space-2);
  transition: border-color var(--transition-base), box-shadow var(--transition-base);
}

.chat-input-wrapper:focus-within {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(124, 58, 237, 0.12);
}

.chat-input {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  line-height: 1.6;
  padding: var(--space-2) var(--space-3);
  resize: none;
  max-height: 120px;
}

.chat-input::placeholder {
  color: var(--text-muted);
}

.chat-send {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-gradient);
  border: none;
  border-radius: var(--radius-md);
  color: white;
  cursor: pointer;
  transition: all var(--transition-base);
  flex-shrink: 0;
}

.chat-send:hover {
  transform: scale(1.05);
  box-shadow: 0 2px 12px rgba(124, 58, 237, 0.4);
}

.chat-send:active {
  transform: scale(0.95);
}

.chat-send:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* ── Profile ──────────────────────────────────────────────── */
.profile-header {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  margin-bottom: var(--space-8);
}

.profile-avatar {
  width: 80px;
  height: 80px;
  border-radius: var(--radius-full);
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  font-weight: 700;
  color: white;
  flex-shrink: 0;
  box-shadow: 0 0 20px rgba(124, 58, 237, 0.3);
}

.profile-name {
  font-size: 1.5rem;
  font-weight: 700;
}

.profile-email {
  color: var(--text-muted);
  font-size: 0.9375rem;
}

.profile-section {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  margin-bottom: var(--space-6);
}

.profile-section-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-3);
  border-bottom: 1px solid var(--border-subtle);
}

/* Achievements */
.achievements-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: var(--space-4);
}

.achievement-badge {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-5);
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  text-align: center;
  transition: all var(--transition-base);
}

.achievement-badge:hover {
  border-color: var(--border-default);
  transform: translateY(-2px);
}

.achievement-badge-icon {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  background: rgba(124, 58, 237, 0.1);
  border: 2px solid rgba(124, 58, 237, 0.2);
}

.achievement-badge.unlocked .achievement-badge-icon {
  background: rgba(124, 58, 237, 0.15);
  border-color: var(--accent-primary);
  box-shadow: 0 0 16px rgba(124, 58, 237, 0.25);
}

.achievement-badge.locked {
  opacity: 0.45;
}

.achievement-badge-name {
  font-size: 0.8125rem;
  font-weight: 600;
}

.achievement-badge-desc {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* ── Quiz Page ────────────────────────────────────────────── */
.quiz-page {
  max-width: 720px;
  margin: 0 auto;
  padding: var(--space-8);
}

.quiz-page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-6);
}

.quiz-question {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  margin-bottom: var(--space-6);
}

.quiz-question-text {
  font-size: 1.25rem;
  font-weight: 600;
  line-height: 1.5;
  margin-bottom: var(--space-6);
}

.quiz-question-number {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-muted);
  margin-bottom: var(--space-3);
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.quiz-option {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-5);
  background: var(--bg-surface);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 0.9375rem;
  font-weight: 500;
  transition: all var(--transition-base);
  user-select: none;
}

.quiz-option:hover {
  border-color: var(--border-strong);
  background: var(--bg-hover);
}

.quiz-option.selected {
  border-color: var(--accent-primary);
  background: rgba(124, 58, 237, 0.08);
  box-shadow: 0 0 0 3px rgba(124, 58, 237, 0.1);
}

.quiz-option.correct {
  border-color: var(--color-success);
  background: var(--color-success-bg);
  box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.1);
}

.quiz-option.correct::before {
  content: '✓';
  color: var(--color-success);
  font-weight: 700;
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: rgba(16, 185, 129, 0.15);
  flex-shrink: 0;
}

.quiz-option.wrong {
  border-color: var(--color-error);
  background: var(--color-error-bg);
  box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.1);
}

.quiz-option.wrong::before {
  content: '✗';
  color: var(--color-error);
  font-weight: 700;
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: rgba(239, 68, 68, 0.15);
  flex-shrink: 0;
}

.quiz-option-marker {
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.06);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-muted);
  flex-shrink: 0;
}

.quiz-option.selected .quiz-option-marker {
  background: var(--accent-primary);
  color: white;
}

.quiz-explanation {
  margin-top: var(--space-4);
  padding: var(--space-4);
  background: rgba(37, 99, 235, 0.08);
  border: 1px solid rgba(37, 99, 235, 0.15);
  border-radius: var(--radius-md);
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ── Flashcard Page ───────────────────────────────────────── */
.flashcard-page {
  max-width: 600px;
  margin: 0 auto;
  padding: var(--space-8);
}

.flashcard-page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-8);
}

.flashcard-container {
  perspective: 1000px;
  width: 100%;
  min-height: 340px;
  margin-bottom: var(--space-6);
}

.flashcard-flipper {
  position: relative;
  width: 100%;
  min-height: 340px;
  transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  transform-style: preserve-3d;
  cursor: pointer;
}

.flashcard.flipped .flashcard-flipper {
  transform: rotateY(180deg);
}

.flashcard-front,
.flashcard-back {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-10);
  border-radius: var(--radius-xl);
  text-align: center;
  border: 1px solid var(--border-subtle);
}

.flashcard-front {
  background: var(--bg-elevated);
}

.flashcard-back {
  background: rgba(124, 58, 237, 0.06);
  border-color: rgba(124, 58, 237, 0.15);
  transform: rotateY(180deg);
}

.flashcard-front-label,
.flashcard-back-label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: var(--space-4);
}

.flashcard-front-text,
.flashcard-back-text {
  font-size: 1.5rem;
  font-weight: 600;
  line-height: 1.4;
  color: var(--text-primary);
}

.flashcard-hint {
  font-size: 0.8125rem;
  color: var(--text-muted);
  margin-top: var(--space-4);
}

.flashcard-actions {
  display: flex;
  justify-content: center;
  gap: var(--space-4);
}

/* ── CAPS Subject Cards ───────────────────────────────────── */
.caps-subject-card {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  padding: var(--space-5);
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-base);
}

.caps-subject-card:hover {
  border-color: var(--border-default);
  transform: translateY(-2px);
  box-shadow: var(--shadow-card-hover);
}

.caps-subject-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  background: rgba(124, 58, 237, 0.1);
  color: var(--accent-primary);
  font-size: 1.25rem;
  flex-shrink: 0;
}

.caps-subject-info {
  flex: 1;
}

.caps-subject-name {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--space-1);
}

.caps-subject-desc {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.caps-subject-progress {
  margin-top: var(--space-2);
}

/* ── Progress Bar ─────────────────────────────────────────── */
.progress-bar {
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-full);
  overflow: hidden;
  position: relative;
}

.progress-bar-fill {
  height: 100%;
  border-radius: var(--radius-full);
  background: var(--accent-gradient);
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
}

.progress-bar-fill::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
  animation: progressShimmer 2s ease-in-out infinite;
}

@keyframes progressShimmer {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(200%); }
}

.progress-bar-lg {
  height: 10px;
}

.progress-bar-sm {
  height: 4px;
}

/* ── Score Display ────────────────────────────────────────── */
.score-display {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.score-circle {
  width: 120px;
  height: 120px;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

.score-circle svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.score-circle-bg {
  fill: none;
  stroke: rgba(255, 255, 255, 0.06);
  stroke-width: 6;
}

.score-circle-fill {
  fill: none;
  stroke: url(#scoreGradient);
  stroke-width: 6;
  stroke-linecap: round;
  transition: stroke-dashoffset 1s cubic-bezier(0.4, 0, 0.2, 1);
}

.score-circle-value {
  position: relative;
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.score-circle-label {
  position: relative;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.score-details {
  flex: 1;
}

.score-detail-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-2) 0;
  font-size: 0.9375rem;
}

.score-detail-row + .score-detail-row {
  border-top: 1px solid var(--border-subtle);
}

/* ── Modals ───────────────────────────────────────────────── */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: var(--z-modal);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-8);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-slow);
}

.modal-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

.modal {
  width: 100%;
  max-width: 520px;
  max-height: 85vh;
  background: var(--bg-surface);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl), 0 0 40px rgba(124, 58, 237, 0.08);
  overflow: hidden;
  transform: scale(0.95) translateY(16px);
  transition: transform var(--transition-slow);
}

.modal-overlay.visible .modal {
  transform: scale(1) translateY(0);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-5) var(--space-6);
  border-bottom: 1px solid var(--border-subtle);
}

.modal-title {
  font-size: 1.125rem;
  font-weight: 600;
}

.modal-close {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  color: var(--text-muted);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 1.125rem;
}

.modal-close:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
}

.modal-body {
  padding: var(--space-6);
  overflow-y: auto;
  max-height: calc(85vh - 140px);
}

.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-6);
  border-top: 1px solid var(--border-subtle);
}

/* ── Toasts ───────────────────────────────────────────────── */
.toast-container {
  position: fixed;
  top: var(--space-5);
  right: var(--space-5);
  z-index: var(--z-toast);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  pointer-events: none;
}

.toast {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-5);
  min-width: 320px;
  max-width: 440px;
  background: var(--bg-surface);
  border: 1px solid var(--border-default);
  border-left: 3px solid var(--accent-primary);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  pointer-events: auto;
  animation: toastIn 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.toast.exiting {
  animation: toastOut 0.3s ease forwards;
}

@keyframes toastIn {
  from {
    opacity: 0;
    transform: translateX(100%) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateX(0) scale(1);
  }
}

@keyframes toastOut {
  to {
    opacity: 0;
    transform: translateX(100%) scale(0.95);
  }
}

.toast-success {
  border-left-color: var(--color-success);
}

.toast-error {
  border-left-color: var(--color-error);
}

.toast-warning {
  border-left-color: var(--color-warning);
}

.toast-icon {
  font-size: 1.125rem;
  flex-shrink: 0;
  margin-top: 1px;
}

.toast-content {
  flex: 1;
}

.toast-title {
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 2px;
}

.toast-message {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.toast-close {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 2px;
  font-size: 1rem;
  line-height: 1;
  transition: color var(--transition-fast);
  flex-shrink: 0;
}

.toast-close:hover {
  color: var(--text-primary);
}

/* ── Loading / Spinner ────────────────────────────────────── */
.loading-overlay {
  position: fixed;
  inset: 0;
  background: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: var(--z-loading);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-5);
}

.spinner {
  width: 40px;
  height: 40px;
  position: relative;
}

.spinner::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 50%;
  border: 3px solid rgba(255, 255, 255, 0.08);
  border-top-color: var(--accent-primary);
  animation: spinnerRotate 0.8s linear infinite;
}

@keyframes spinnerRotate {
  to { transform: rotate(360deg); }
}

.spinner-lg {
  width: 56px;
  height: 56px;
}

.spinner-lg::before {
  border-width: 4px;
}

.spinner-sm {
  width: 24px;
  height: 24px;
}

.spinner-sm::before {
  border-width: 2px;
}

.spinner-gradient {
  background: conic-gradient(from 0deg, transparent, var(--accent-primary), transparent);
  border-radius: 50%;
  animation: spinnerRotate 1s linear infinite;
  mask: radial-gradient(farthest-side, transparent calc(100% - 3px), #fff calc(100% - 3px));
  -webkit-mask: radial-gradient(farthest-side, transparent calc(100% - 3px), #fff calc(100% - 3px));
}

.loading-text {
  font-size: 0.9375rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ── Empty State ──────────────────────────────────────────── */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-16) var(--space-8);
  text-align: center;
}

.empty-state-icon {
  font-size: 3rem;
  margin-bottom: var(--space-4);
  opacity: 0.5;
}

.empty-state-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--space-2);
}

.empty-state-desc {
  font-size: 0.9375rem;
  color: var(--text-muted);
  max-width: 360px;
  margin-bottom: var(--space-6);
}

/* ── Filter Chips ─────────────────────────────────────────── */
.filter-chip {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 5px 14px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: transparent;
  border: 1px solid var(--border-default);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.filter-chip:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: var(--border-strong);
}

.filter-chip.active {
  background: rgba(124, 58, 237, 0.12);
  border-color: rgba(124, 58, 237, 0.3);
  color: var(--accent-primary);
}

.filter-chips {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

/* ── Utility Classes ──────────────────────────────────────── */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.gap-1 { gap: var(--space-1); }
.gap-2 { gap: var(--space-2); }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

.mt-1 { margin-top: var(--space-1); }
.mt-2 { margin-top: var(--space-2); }
.mt-3 { margin-top: var(--space-3); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }
.mb-1 { margin-bottom: var(--space-1); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-3 { margin-bottom: var(--space-3); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

.w-full { width: 100%; }
.hidden { display: none !important; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.truncate {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.rounded { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-full { border-radius: var(--radius-full); }

/* ── App Layout ───────────────────────────────────────────── */
.app-layout {
  display: flex;
  min-height: 100vh;
}

.app-main {
  flex: 1;
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.app-content {
  flex: 1;
  padding: var(--space-8);
  max-width: 1200px;
}

/* ── Page Transitions ─────────────────────────────────────── */
.page-enter {
  animation: pageIn 0.3s ease;
}

@keyframes pageIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ── Code / Markdown in Messages ──────────────────────────── */
.message-bubble h1,
.message-bubble h2,
.message-bubble h3,
.message-bubble h4 {
  color: var(--text-primary);
  margin-top: var(--space-4);
  margin-bottom: var(--space-2);
}

.message-bubble ul,
.message-bubble ol {
  padding-left: var(--space-5);
  margin: var(--space-2) 0;
}

.message-bubble li {
  margin-bottom: var(--space-1);
}

.message-bubble strong {
  color: var(--text-primary);
  font-weight: 600;
}

.message-bubble blockquote {
  border-left: 3px solid var(--accent-primary);
  padding-left: var(--space-4);
  color: var(--text-secondary);
  margin: var(--space-3) 0;
  font-style: italic;
}

/* ── Tabs ─────────────────────────────────────────────────── */
.tabs {
  display: flex;
  gap: var(--space-1);
  padding: 3px;
  background: rgba(255, 255, 255, 0.04);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-6);
}

.tab {
  flex: 1;
  padding: var(--space-2) var(--space-4);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-muted);
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
}

.tab:hover {
  color: var(--text-secondary);
}

.tab.active {
  color: var(--text-primary);
  background: var(--bg-elevated);
  box-shadow: var(--shadow-sm);
}

/* ── Dropdown ─────────────────────────────────────────────── */
.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-menu {
  position: absolute;
  top: calc(100% + 4px);
  right: 0;
  min-width: 180px;
  background: var(--bg-surface);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  padding: var(--space-1);
  z-index: 50;
  opacity: 0;
  transform: translateY(-4px);
  pointer-events: none;
  transition: all var(--transition-fast);
}

.dropdown-menu.visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.dropdown-item {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  font-size: 0.875rem;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: none;
  background: none;
  width: 100%;
  text-align: left;
}

.dropdown-item:hover {
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-primary);
}

.dropdown-divider {
  height: 1px;
  background: var(--border-subtle);
  margin: var(--space-1) 0;
}

/* ── Tooltip ──────────────────────────────────────────────── */
.tooltip {
  position: relative;
}

.tooltip::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  padding: 4px 10px;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-primary);
  background: var(--bg-elevated);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-sm);
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: all var(--transition-fast);
  z-index: 50;
}

.tooltip:hover::after {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ── Skeleton Loading ─────────────────────────────────────── */
.skeleton {
  background: linear-gradient(90deg, var(--bg-elevated) 25%, var(--bg-hover) 50%, var(--bg-elevated) 75%);
  background-size: 200% 100%;
  animation: skeletonShimmer 1.5s ease-in-out infinite;
  border-radius: var(--radius-sm);
}

@keyframes skeletonShimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.skeleton-text {
  height: 14px;
  margin-bottom: var(--space-2);
}

.skeleton-text:last-child {
  width: 60%;
}

.skeleton-circle {
  border-radius: 50%;
}

.skeleton-card {
  height: 180px;
  border-radius: var(--radius-lg);
}

/* ── Responsive ───────────────────────────────────────────── */
@media (max-width: 1024px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .app-main {
    margin-left: 0;
  }

  .hamburger-btn {
    display: flex;
  }

  .landing-nav-links {
    display: none;
  }

  .hero-stats {
    gap: var(--space-8);
  }
}

@media (max-width: 768px) {
  :root {
    --space-8: 24px;
    --space-12: 32px;
    --space-16: 48px;
  }

  .app-main {
    padding-bottom: var(--bottom-nav-height);
  }

  
/* ── Page Layout with Sidebar ────────────────────────────── */
.page-with-sidebar {
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  padding-bottom: var(--space-8);
}

@media (max-width: 1024px) {
  .page-with-sidebar {
    margin-left: 0;
    padding-bottom: calc(var(--bottom-nav-height) + var(--space-6));
  }
}

.bottom-nav {
    display: flex;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .hero-stats {
    flex-direction: column;
    gap: var(--space-6);
  }

  .hero-actions {
    flex-direction: column;
    width: 100%;
  }

  .hero-actions .btn {
    width: 100%;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .pricing-grid {
    grid-template-columns: 1fr;
  }

  .testimonials-grid {
    grid-template-columns: 1fr;
  }

  .dashboard-stats {
    grid-template-columns: repeat(2, 1fr);
  }

  .chat-messages {
    padding: var(--space-4);
  }

  .chat-input-area {
    padding: var(--space-3) var(--space-4) var(--space-4);
  }

  .auth-card {
    padding: var(--space-6);
  }

  .achievements-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .quiz-page,
  .flashcard-page {
    padding: var(--space-4);
  }

  .flashcard-container {
    min-height: 280px;
  }

  .flashcard-flipper {
    min-height: 280px;
  }

  .toast {
    min-width: auto;
    max-width: calc(100vw - 40px);
  }

  .toast-container {
    left: var(--space-3);
    right: var(--space-3);
  }

  .score-display {
    flex-direction: column;
  }

  .landing-nav {
    padding: var(--space-3) var(--space-4);
  }

  .section-header h2 {
    font-size: 1.75rem;
  }
}

@media (max-width: 480px) {
  .dashboard-stats {
    grid-template-columns: 1fr;
  }

  .dashboard-modules {
    grid-template-columns: 1fr;
  }

  .profile-header {
    flex-direction: column;
    text-align: center;
  }

  .achievements-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .modal {
    margin: var(--space-4);
    max-height: calc(100vh - 32px);
  }
}

/* ── Print ────────────────────────────────────────────────── */
@media print {
  .sidebar,
  .bottom-nav,
  .hamburger-btn,
  .toast-container,
  .loading-overlay {
    display: none !important;
  }

  .app-main {
    margin-left: 0;
  }

  body {
    background: white;
    color: #111;
  }

  .card,
  .feature-card,
  .pricing-card {
    border: 1px solid #ddd;
    box-shadow: none;
  }
}

/* ── Accessibility: Reduced Motion ────────────────────────── */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .hero-orb {
    animation: none;
  }

  .flashcard-flipper {
    transition: none;
  }
}

/* ── Accessibility: Focus Visible ─────────────────────────── */
:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* ── High Contrast Mode ───────────────────────────────────── */
@media (forced-colors: active) {
  .btn-primary {
    border: 2px solid ButtonText;
  }

  .card,
  .feature-card,
  .pricing-card {
    border: 1px solid CanvasText;
  }
}


/* ── Bottom Nav Chat Spacing ─────────────────────────────── */
@media (max-width: 1024px) {
  .chat-input-area {
    padding-bottom: calc(var(--bottom-nav-height) + var(--space-4));
  }
}