/* ============================================
   BISMUTH — CalculateYourGPA.com
   Core Design System
   ============================================ */

/* --- CSS Custom Properties (Theme) --- */
:root {
  /* Brand Colors */
  --brand-primary: #2563eb;
  --brand-primary-light: #3b82f6;
  --brand-primary-dark: #1d4ed8;
  --brand-accent: #06b6d4;
  --brand-accent-light: #22d3ee;
  --brand-bismuth: #7c3aed;

  /* Neutrals */
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;

  /* Semantic */
  --color-success: #16a34a;
  --color-success-bg: #f0fdf4;
  --color-warning: #d97706;
  --color-warning-bg: #fffbeb;
  --color-error: #dc2626;
  --color-error-bg: #fef2f2;
  --color-info: #2563eb;
  --color-info-bg: #eff6ff;

  /* Aliases (shorthand used in inline styles) */
  --success: var(--color-success);
  --success-bg: var(--color-success-bg);
  --warning: var(--color-warning);
  --warning-bg: var(--color-warning-bg);
  --error: var(--color-error);
  --error-bg: var(--color-error-bg);
  --info: var(--color-info);
  --info-bg: var(--color-info-bg);
  --primary: var(--brand-primary);

  /* Surfaces */
  --bg-body: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-raised: #ffffff;
  --bg-surface-hover: #f1f5f9;
  --bg-surface-active: #e2e8f0;
  --bg-overlay: rgba(15, 23, 42, 0.5);

  /* Text */
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-tertiary: #94a3b8;
  --text-inverse: #ffffff;
  --text-link: #2563eb;

  /* Borders */
  --border-color: #e2e8f0;
  --border-color-strong: #cbd5e1;
  --border-radius-sm: 6px;
  --border-radius: 8px;
  --border-radius-md: 12px;
  --border-radius-lg: 16px;
  --border-radius-xl: 24px;
  --border-radius-full: 9999px;

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.08), 0 2px 4px -2px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -4px rgba(0,0,0,0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.04);

  /* 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', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;

  /* Z-index */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-modal-backdrop: 300;
  --z-modal: 400;
  --z-toast: 500;
  --z-tooltip: 600;
  --z-tour: 700;

  /* Layout */
  --header-height: 64px;
  --sidebar-width: 340px;
  --max-width: 1280px;
  --max-width-narrow: 800px;
}

/* --- Dark Mode --- */
[data-theme="dark"] {
  --bg-body: #0f172a;
  --bg-surface: #1e293b;
  --bg-surface-raised: #334155;
  --bg-surface-hover: #334155;
  --bg-surface-active: #475569;
  --bg-overlay: rgba(0, 0, 0, 0.6);

  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-tertiary: #64748b;
  --text-link: #60a5fa;

  --border-color: #334155;
  --border-color-strong: #475569;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.3);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.4);

  --color-success-bg: #052e16;
  --color-warning-bg: #451a03;
  --color-error-bg: #450a0a;
  --color-info-bg: #172554;

  --success-bg: var(--color-success-bg);
  --warning-bg: var(--color-warning-bg);
  --error-bg: var(--color-error-bg);
  --info-bg: var(--color-info-bg);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--text-primary);
  background-color: var(--bg-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--text-link);
  text-decoration: none;
  transition: color var(--transition-fast);
}
a:hover { text-decoration: underline; }
a:focus-visible {
  outline: 2px solid var(--brand-primary);
  outline-offset: 2px;
  border-radius: 2px;
}

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

button, input, select, textarea {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
  color: inherit;
}

button { cursor: pointer; }

h1, h2, h3, h4, h5, h6 {
  line-height: var(--line-height-tight);
  font-weight: 700;
  color: var(--text-primary);
}
h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }
h5 { font-size: var(--font-size-lg); }

p { margin-bottom: var(--space-4); color: var(--text-secondary); }
p:last-child { margin-bottom: 0; }

ul, ol { padding-left: var(--space-6); }
li { margin-bottom: var(--space-2); }

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

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

.text-center { text-align: center; }
.text-sm { font-size: var(--font-size-sm); }
.text-xs { font-size: var(--font-size-xs); }
.text-secondary { color: var(--text-secondary); }
.text-tertiary { color: var(--text-tertiary); }
.text-success { color: var(--color-success); }
.text-warning { color: var(--color-warning); }
.text-error { color: var(--color-error); }
.font-mono { font-family: var(--font-mono); }
.font-bold { font-weight: 700; }
.font-semibold { font-weight: 600; }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.items-center { align-items: center; }
.items-start { align-items: flex-start; }
.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); }

.grid { display: grid; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

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

.hidden { display: none !important; }
.visible { display: block !important; }

/* --- Header --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  height: var(--header-height);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.header-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 700;
  font-size: var(--font-size-lg);
}
.header-logo:hover { text-decoration: none; }

.header-logo svg {
  width: 32px;
  height: 32px;
  flex-shrink: 0;
}

.logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}
.logo-text .brand-name {
  font-size: var(--font-size-lg);
  font-weight: 800;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-bismuth));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.logo-text .brand-sub {
  font-size: 10px;
  font-weight: 500;
  color: var(--text-tertiary);
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.header-nav a {
  padding: var(--space-2) var(--space-3);
  border-radius: var(--border-radius-sm);
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  font-weight: 500;
  transition: all var(--transition-fast);
}
.header-nav a:hover {
  color: var(--text-primary);
  background: var(--bg-surface-hover);
  text-decoration: none;
}
.header-nav a.active {
  color: var(--brand-primary);
  background: var(--color-info-bg);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* Search Bar */
.header-search {
  position: relative;
  width: 220px;
}
.header-search input {
  width: 100%;
  padding: var(--space-2) var(--space-3) var(--space-2) 36px;
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-full);
  background: var(--bg-surface-hover);
  font-size: var(--font-size-sm);
  transition: all var(--transition-fast);
}
.header-search input:focus {
  outline: none;
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
  background: var(--bg-surface);
}
.header-search .search-icon {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  width: 16px;
  height: 16px;
  color: var(--text-tertiary);
  pointer-events: none;
}
.search-results-dropdown {
  position: absolute;
  top: calc(100% + 4px);
  left: 0;
  right: 0;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-lg);
  max-height: 300px;
  overflow-y: auto;
  display: none;
  z-index: var(--z-dropdown);
}
.search-results-dropdown.show { display: block; }
.search-result-item {
  display: block;
  padding: var(--space-3) var(--space-4);
  color: var(--text-primary);
  font-size: var(--font-size-sm);
  border-bottom: 1px solid var(--border-color);
  transition: background var(--transition-fast);
}
.search-result-item:last-child { border-bottom: none; }
.search-result-item:hover {
  background: var(--bg-surface-hover);
  text-decoration: none;
}
.search-result-item .result-title { font-weight: 600; }
.search-result-item .result-desc {
  font-size: var(--font-size-xs);
  color: var(--text-tertiary);
  margin-top: 2px;
}

/* Theme Toggle */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  background: var(--bg-surface);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}
.theme-toggle:hover {
  background: var(--bg-surface-hover);
  color: var(--text-primary);
}
.theme-toggle svg { width: 18px; height: 18px; }

/* Mobile Menu */
.mobile-menu-btn {
  display: none;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: none;
  background: none;
  color: var(--text-primary);
}
.mobile-menu-btn svg { width: 24px; height: 24px; }

/* --- Footer --- */
.site-footer {
  margin-top: auto;
  border-top: 1px solid var(--border-color);
  background: var(--bg-surface);
  padding: var(--space-12) 0 var(--space-8);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

.footer-brand .brand-name {
  font-size: var(--font-size-xl);
  font-weight: 800;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-bismuth));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--space-2);
}
.footer-brand .brand-tagline {
  color: var(--text-tertiary);
  font-size: var(--font-size-sm);
  margin-bottom: var(--space-4);
}

.footer-trust {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.footer-trust-item {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--font-size-xs);
  color: var(--text-tertiary);
}
.footer-trust-item svg {
  width: 14px;
  height: 14px;
  color: var(--color-success);
  flex-shrink: 0;
}

.footer-col h4 {
  font-size: var(--font-size-sm);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-tertiary);
  margin-bottom: var(--space-4);
}
.footer-col ul { list-style: none; padding: 0; }
.footer-col li { margin-bottom: var(--space-2); }
.footer-col a {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  transition: color var(--transition-fast);
}
.footer-col a:hover { color: var(--text-primary); }

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: var(--font-size-xs);
  color: var(--text-tertiary);
}

.footer-disclaimer {
  max-width: 600px;
  font-size: var(--font-size-xs);
  color: var(--text-tertiary);
  line-height: var(--line-height-relaxed);
}

/* --- Breadcrumb --- */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--font-size-sm);
  color: var(--text-tertiary);
  padding: var(--space-4) 0;
}
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--text-link); }
.breadcrumb .separator { color: var(--text-tertiary); }
.breadcrumb .current { color: var(--text-primary); font-weight: 500; }

/* --- Page Layout --- */
.page-hero {
  padding: var(--space-10) 0 var(--space-8);
  text-align: center;
}
.page-hero h1 {
  margin-bottom: var(--space-4);
  font-size: var(--font-size-4xl);
}
.page-hero .hero-subtitle {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

.page-content {
  flex: 1;
  padding: var(--space-6) 0 var(--space-16);
}

/* Calculator Split Layout */
.calc-layout {
  display: grid;
  grid-template-columns: 1fr var(--sidebar-width);
  gap: var(--space-6);
  align-items: start;
  min-height: calc(100vh - var(--header-height) - 120px);
}
.calc-main { min-width: 0; }
.calc-sidebar {
  position: sticky;
  top: calc(var(--header-height) + var(--space-4));
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border: 1px solid transparent;
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 600;
  text-decoration: none;
  transition: all var(--transition-fast);
  white-space: nowrap;
  cursor: pointer;
  line-height: 1.5;
}
.btn:hover { text-decoration: none; }
.btn:focus-visible {
  outline: 2px solid var(--brand-primary);
  outline-offset: 2px;
}
.btn svg { width: 16px; height: 16px; flex-shrink: 0; }

.btn-primary {
  background: var(--brand-primary);
  color: var(--text-inverse);
  border-color: var(--brand-primary);
}
.btn-primary:hover {
  background: var(--brand-primary-dark);
  border-color: var(--brand-primary-dark);
}

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

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border-color: transparent;
}
.btn-ghost:hover {
  background: var(--bg-surface-hover);
  color: var(--text-primary);
}

.btn-danger {
  background: var(--color-error);
  color: var(--text-inverse);
  border-color: var(--color-error);
}
.btn-danger:hover {
  background: #b91c1c;
  border-color: #b91c1c;
}

.btn-success {
  background: var(--color-success);
  color: var(--text-inverse);
}
.btn-success:hover { background: #15803d; }

.btn-sm {
  padding: var(--space-1) var(--space-3);
  font-size: var(--font-size-xs);
}

.btn-lg {
  padding: var(--space-3) var(--space-6);
  font-size: var(--font-size-base);
  border-radius: var(--border-radius);
}

.btn-icon {
  width: 36px;
  height: 36px;
  padding: 0;
  border-radius: var(--border-radius-sm);
}

.btn-group {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

/* --- Cards --- */
.card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition-base), transform var(--transition-base);
}
.card-hover:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-4);
}
.card-title {
  font-size: var(--font-size-lg);
  font-weight: 700;
}
.card-subtitle {
  font-size: var(--font-size-sm);
  color: var(--text-tertiary);
  margin-top: var(--space-1);
}

/* --- Form Elements --- */
.form-group {
  margin-bottom: var(--space-4);
}
.form-label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-1);
}
.form-hint {
  font-size: var(--font-size-xs);
  color: var(--text-tertiary);
  margin-top: var(--space-1);
}

.form-input,
.form-select {
  width: 100%;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  background: var(--bg-surface);
  font-size: var(--font-size-sm);
  transition: all var(--transition-fast);
  color: var(--text-primary);
}
.form-input:focus,
.form-select:focus {
  outline: none;
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}
.form-input.error {
  border-color: var(--color-error);
  box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.1);
}
.form-input::placeholder { color: var(--text-tertiary); }

.form-select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 8px center;
  padding-right: 32px;
}

.form-checkbox {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  cursor: pointer;
  font-size: var(--font-size-sm);
}
.form-checkbox input[type="checkbox"] {
  width: 16px;
  height: 16px;
  border-radius: 3px;
  accent-color: var(--brand-primary);
}

.form-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-4);
}

/* Toggle Switch */
.toggle-switch {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  cursor: pointer;
  font-size: var(--font-size-sm);
}
.toggle-switch input { position: absolute; opacity: 0; width: 0; height: 0; }
.toggle-slider {
  width: 40px;
  height: 22px;
  background: var(--gray-300);
  border-radius: 11px;
  transition: background var(--transition-fast);
  position: relative;
}
.toggle-slider::after {
  content: '';
  position: absolute;
  left: 3px;
  top: 3px;
  width: 16px;
  height: 16px;
  background: white;
  border-radius: 50%;
  transition: transform var(--transition-fast);
}
.toggle-switch input:checked + .toggle-slider {
  background: var(--brand-primary);
}
.toggle-switch input:checked + .toggle-slider::after {
  transform: translateX(18px);
}
.toggle-switch input:focus-visible + .toggle-slider {
  outline: 2px solid var(--brand-primary);
  outline-offset: 2px;
}

/* --- Tabs --- */
.tabs {
  display: flex;
  border-bottom: 2px solid var(--border-color);
  gap: 0;
  overflow-x: auto;
}
.tab-btn {
  padding: var(--space-3) var(--space-4);
  border: none;
  background: none;
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  font-weight: 600;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  white-space: nowrap;
  transition: all var(--transition-fast);
}
.tab-btn:hover { color: var(--text-primary); }
.tab-btn.active {
  color: var(--brand-primary);
  border-bottom-color: var(--brand-primary);
}
.tab-panel { display: none; padding-top: var(--space-4); }
.tab-panel.active { display: block; }

/* --- Badge --- */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px var(--space-2);
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  border-radius: var(--border-radius-full);
  line-height: 1.4;
}
.badge-info { background: var(--color-info-bg); color: var(--brand-primary); }
.badge-success { background: var(--color-success-bg); color: var(--color-success); }
.badge-warning { background: var(--color-warning-bg); color: var(--color-warning); }
.badge-error { background: var(--color-error-bg); color: var(--color-error); }
.badge-neutral { background: var(--gray-200); color: var(--gray-600); }
[data-theme="dark"] .badge-neutral { background: var(--gray-700); color: var(--gray-300); }

/* --- Toast --- */
.toast-container {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  z-index: var(--z-toast);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.toast {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-lg);
  font-size: var(--font-size-sm);
  transform: translateX(120%);
  transition: transform var(--transition-slow);
  max-width: 360px;
}
.toast.show { transform: translateX(0); }
.toast.toast-success { border-left: 3px solid var(--color-success); }
.toast.toast-error { border-left: 3px solid var(--color-error); }
.toast.toast-info { border-left: 3px solid var(--brand-primary); }

/* --- Modal --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--bg-overlay);
  z-index: var(--z-modal-backdrop);
  display: none;
  align-items: center;
  justify-content: center;
  padding: var(--space-6);
}
.modal-overlay.show { display: flex; }

.modal {
  background: var(--bg-surface);
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-xl);
  max-width: 560px;
  width: 100%;
  max-height: 80vh;
  overflow-y: auto;
  animation: modalIn var(--transition-slow) ease;
}
@keyframes modalIn {
  from { opacity: 0; transform: scale(0.95) translateY(10px); }
  to { opacity: 1; transform: scale(1) translateY(0); }
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-6);
  border-bottom: 1px solid var(--border-color);
}
.modal-header h3 { margin: 0; font-size: var(--font-size-xl); }

.modal-body { padding: var(--space-6); }

.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-color);
}

.modal-close {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  background: none;
  color: var(--text-tertiary);
  border-radius: var(--border-radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}
.modal-close:hover {
  background: var(--bg-surface-hover);
  color: var(--text-primary);
}

/* --- Tooltip --- */
.tooltip-wrapper { position: relative; }
.tooltip {
  position: absolute;
  bottom: calc(100% + 6px);
  left: 50%;
  transform: translateX(-50%);
  padding: var(--space-2) var(--space-3);
  background: var(--gray-800);
  color: white;
  font-size: var(--font-size-xs);
  border-radius: var(--border-radius-sm);
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: opacity var(--transition-fast);
  z-index: var(--z-tooltip);
}
.tooltip::after {
  content: '';
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  border: 4px solid transparent;
  border-top-color: var(--gray-800);
}
.tooltip-wrapper:hover .tooltip,
.tooltip-wrapper:focus-within .tooltip { opacity: 1; }

/* --- Accordion / FAQ --- */
.accordion { border: 1px solid var(--border-color); border-radius: var(--border-radius-md); overflow: hidden; }
.accordion-item { border-bottom: 1px solid var(--border-color); }
.accordion-item:last-child { border-bottom: none; }

.accordion-trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: var(--space-4) var(--space-5);
  border: none;
  background: none;
  font-size: var(--font-size-base);
  font-weight: 600;
  text-align: left;
  cursor: pointer;
  color: var(--text-primary);
  transition: background var(--transition-fast);
}
.accordion-trigger:hover { background: var(--bg-surface-hover); }
.accordion-trigger svg {
  width: 18px;
  height: 18px;
  color: var(--text-tertiary);
  transition: transform var(--transition-base);
  flex-shrink: 0;
}
.accordion-item.open .accordion-trigger svg { transform: rotate(180deg); }

.accordion-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow);
}
.accordion-content-inner {
  padding: 0 var(--space-5) var(--space-4);
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  line-height: var(--line-height-relaxed);
}

/* --- GPA Result Display --- */
.gpa-display {
  text-align: center;
  padding: var(--space-6);
}
.gpa-number {
  font-size: var(--font-size-5xl);
  font-weight: 800;
  line-height: 1;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-bismuth));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--space-2);
}
.gpa-label {
  font-size: var(--font-size-sm);
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-weight: 600;
}
.gpa-stats {
  display: flex;
  justify-content: center;
  gap: var(--space-6);
  margin-top: var(--space-4);
  padding-top: var(--space-4);
  border-top: 1px solid var(--border-color);
}
.gpa-stat-item {
  text-align: center;
}
.gpa-stat-value {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
}
.gpa-stat-label {
  font-size: var(--font-size-xs);
  color: var(--text-tertiary);
}

/* --- Insight Panel (BISMUTH Insight) --- */
.insight-panel {
  background: linear-gradient(135deg, rgba(37, 99, 235, 0.05), rgba(124, 58, 237, 0.05));
  border: 1px solid rgba(37, 99, 235, 0.15);
  border-radius: var(--border-radius-md);
  padding: var(--space-4);
}
.insight-header {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--font-size-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--brand-bismuth);
  margin-bottom: var(--space-3);
}
.insight-header svg {
  width: 14px;
  height: 14px;
}
.insight-content {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  line-height: var(--line-height-relaxed);
}

/* --- Ad Slots --- */
.ad-slot {
  min-height: 0;
  display: none; /* hidden until ads enabled */
}
.ad-slot[data-ad-active="true"] {
  display: block;
  min-height: 90px;
  background: var(--bg-surface-hover);
  border: 1px dashed var(--border-color);
  border-radius: var(--border-radius);
}

/* --- Meter / Progress --- */
.meter {
  width: 100%;
  height: 8px;
  background: var(--gray-200);
  border-radius: var(--border-radius-full);
  overflow: hidden;
}
.meter-fill {
  height: 100%;
  border-radius: var(--border-radius-full);
  transition: width var(--transition-slow), background var(--transition-slow);
}
.meter-fill.easy { background: var(--color-success); }
.meter-fill.moderate { background: var(--color-warning); }
.meter-fill.hard { background: var(--color-error); }

/* --- Tour Overlay --- */
.tour-overlay {
  position: fixed;
  inset: 0;
  z-index: var(--z-tour);
  pointer-events: none;
}
.tour-highlight {
  position: absolute;
  box-shadow: 0 0 0 4000px rgba(0, 0, 0, 0.5);
  border-radius: var(--border-radius);
  pointer-events: none;
  transition: all var(--transition-slow);
}
.tour-tooltip {
  position: absolute;
  background: var(--bg-surface);
  border-radius: var(--border-radius-md);
  padding: var(--space-5);
  box-shadow: var(--shadow-xl);
  max-width: 320px;
  pointer-events: all;
  z-index: calc(var(--z-tour) + 1);
}
.tour-tooltip h4 { margin-bottom: var(--space-2); }
.tour-tooltip p { font-size: var(--font-size-sm); color: var(--text-secondary); margin-bottom: var(--space-4); }
.tour-actions { display: flex; justify-content: space-between; align-items: center; }
.tour-dots {
  display: flex;
  gap: var(--space-1);
}
.tour-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--gray-300);
}
.tour-dot.active { background: var(--brand-primary); }

/* --- Slide-up Sheet (Mobile) --- */
.slide-sheet {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--bg-surface);
  border-radius: var(--border-radius-lg) var(--border-radius-lg) 0 0;
  box-shadow: var(--shadow-xl);
  transform: translateY(100%);
  transition: transform var(--transition-slow);
  z-index: var(--z-modal);
  max-height: 80vh;
  overflow-y: auto;
}
.slide-sheet.open { transform: translateY(0); }
.slide-sheet-handle {
  width: 36px;
  height: 4px;
  background: var(--gray-300);
  border-radius: 2px;
  margin: var(--space-3) auto var(--space-2);
}

/* --- Mobile Sticky Bar --- */
.mobile-sticky-bar {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: var(--space-3) var(--space-4);
  z-index: var(--z-sticky);
  box-shadow: 0 -4px 12px rgba(0,0,0,0.1);
}
.mobile-sticky-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}
.mobile-gpa-mini {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.mobile-gpa-mini .gpa-val {
  font-size: var(--font-size-2xl);
  font-weight: 800;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-bismuth));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.mobile-gpa-mini .gpa-meta {
  font-size: var(--font-size-xs);
  color: var(--text-tertiary);
}

/* --- Responsive --- */
@media (max-width: 1024px) {
  .calc-layout {
    grid-template-columns: 1fr;
  }
  .calc-sidebar {
    position: static;
  }
}

@media (max-width: 768px) {
  :root {
    --header-height: 56px;
  }

  h1 { font-size: var(--font-size-3xl); }
  h2 { font-size: var(--font-size-2xl); }

  .container { padding: 0 var(--space-4); }

  .mobile-menu-btn { display: flex; }

  .header-nav {
    display: none;
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-surface);
    flex-direction: column;
    padding: var(--space-6);
    z-index: var(--z-modal);
    overflow-y: auto;
  }
  .header-nav.open { display: flex; }
  .header-nav a {
    padding: var(--space-3) var(--space-4);
    font-size: var(--font-size-base);
  }

  .header-search { width: 100%; max-width: 200px; }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: var(--space-6);
  }

  .footer-bottom {
    flex-direction: column;
    gap: var(--space-3);
    text-align: center;
  }

  .page-hero { padding: var(--space-6) 0; }
  .page-hero h1 { font-size: var(--font-size-2xl); }

  .mobile-sticky-bar { display: block; }
  body.has-mobile-bar { padding-bottom: 72px; }

  .form-row { grid-template-columns: 1fr; }

  .gpa-stats { flex-direction: column; gap: var(--space-3); }

  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }

  .toast-container { left: var(--space-4); right: var(--space-4); bottom: 80px; }
  .toast { max-width: none; }
}

@media (max-width: 480px) {
  .btn-group { flex-direction: column; }
  .btn-group .btn { width: 100%; }
}

/* --- Print Styles --- */
@media print {
  .site-header, .site-footer, .mobile-sticky-bar,
  .toast-container, .ad-slot, .btn-group, .theme-toggle { display: none !important; }
  body { background: white; color: black; }
  .card { border: 1px solid #ddd; box-shadow: none; }
  .gpa-number {
    -webkit-text-fill-color: #2563eb;
    color: #2563eb;
  }
}

/* --- Content Article (Guides, Policies, Info Pages) --- */
.content-article {
  line-height: var(--line-height-relaxed);
}
.content-article h1 {
  font-size: var(--font-size-4xl);
  margin-bottom: var(--space-4);
}
.content-article h2 {
  font-size: var(--font-size-2xl);
  margin-top: var(--space-8);
  margin-bottom: var(--space-4);
  padding-top: var(--space-4);
  border-top: 1px solid var(--border-color);
}
.content-article h2:first-of-type {
  border-top: none;
  padding-top: 0;
}
.content-article h3 {
  font-size: var(--font-size-xl);
  margin-top: var(--space-6);
  margin-bottom: var(--space-3);
}
.content-article p {
  margin-bottom: var(--space-4);
  color: var(--text-secondary);
  line-height: var(--line-height-relaxed);
}
.content-article ul,
.content-article ol {
  margin-bottom: var(--space-4);
  padding-left: var(--space-6);
}
.content-article li {
  margin-bottom: var(--space-2);
  color: var(--text-secondary);
  line-height: var(--line-height-relaxed);
}
.content-article a {
  color: var(--text-link);
  font-weight: 500;
}
.content-article strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* --- Tables --- */
.table-responsive {
  overflow-x: auto;
  border-radius: var(--border-radius-md);
  border: 1px solid var(--border-color);
}
.table-responsive table,
.content-article table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--font-size-sm);
  background: var(--bg-surface);
}
.table-responsive th,
.content-article th {
  padding: var(--space-3) var(--space-4);
  text-align: left;
  font-weight: 700;
  font-size: var(--font-size-xs);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-tertiary);
  background: var(--bg-surface-hover);
  border-bottom: 2px solid var(--border-color);
  white-space: nowrap;
}
.table-responsive td,
.content-article td {
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--border-color);
  color: var(--text-secondary);
  vertical-align: top;
}
.table-responsive tr:last-child td,
.content-article tr:last-child td {
  border-bottom: none;
}
.table-responsive tr:hover td,
.content-article tr:hover td {
  background: var(--bg-surface-hover);
}

/* --- FAQ / Details Elements --- */
.faq-item {
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  margin-bottom: var(--space-3);
  overflow: hidden;
  transition: border-color var(--transition-fast);
}
.faq-item[open] {
  border-color: var(--brand-primary);
}
.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-5);
  font-weight: 600;
  font-size: var(--font-size-base);
  color: var(--text-primary);
  cursor: pointer;
  user-select: none;
  list-style: none;
  transition: background var(--transition-fast);
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: '+';
  font-size: var(--font-size-xl);
  font-weight: 300;
  color: var(--text-tertiary);
  transition: transform var(--transition-base);
  flex-shrink: 0;
  margin-left: var(--space-4);
}
.faq-item[open] summary::after {
  content: '−';
  color: var(--brand-primary);
}
.faq-item summary:hover {
  background: var(--bg-surface-hover);
}
.faq-item > p,
.faq-item > div {
  padding: 0 var(--space-5) var(--space-4);
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  line-height: var(--line-height-relaxed);
}

/* --- .input alias (used on info/form pages) --- */
.input {
  width: 100%;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  background: var(--bg-surface);
  font-size: var(--font-size-sm);
  transition: all var(--transition-fast);
  color: var(--text-primary);
}
.input:focus {
  outline: none;
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}
.input::placeholder { color: var(--text-tertiary); }
select.input {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 8px center;
  padding-right: 32px;
}
textarea.input {
  min-height: 80px;
}

/* --- Form group label styling --- */
.form-group label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-1);
}

/* --- Animations --- */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}
@keyframes slideUp {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}
.animate-fade-in { animation: fadeIn var(--transition-slow) ease; }
.animate-slide-up { animation: slideUp var(--transition-slow) ease; }