/* ============================================
   MSIB.io — Medical School in a Box
   Core Stylesheet
   ============================================ */

/* --- CSS Variables / Design Tokens --- */
:root {
  /* Stanford-inspired palette */
  --color-primary: #8C1515;       /* Stanford cardinal */
  --color-primary-dark: #6B0F0F;
  --color-primary-light: #B83A3A;
  --color-secondary: #2E4057;     /* Deep navy for text/headers */
  --color-accent: #007C92;        /* Teal for interactive elements */
  --color-accent-light: #00A3B5;
  --color-success: #2D8659;
  --color-warning: #E98300;
  --color-bg: #FAFAFA;
  --color-surface: #FFFFFF;
  --color-surface-alt: #F5F3F0;
  --color-border: #E0DCD8;
  --color-text: #2E2D29;
  --color-text-secondary: #585754;
  --color-text-muted: #8B8A88;

  /* Typography */
  --font-heading: 'Source Serif 4', 'Georgia', serif;
  --font-body: 'Source Sans 3', 'Helvetica Neue', sans-serif;
  --font-mono: 'Source Code Pro', 'Menlo', monospace;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Layout */
  --max-width: 1200px;
  --sidebar-width: 280px;
  --radius: 8px;
  --radius-sm: 4px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
}

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

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  color: var(--color-secondary);
  line-height: 1.3;
  margin-bottom: var(--space-sm);
}

h1 { font-size: 2.25rem; }
h2 { font-size: 1.75rem; }
h3 { font-size: 1.375rem; }
h4 { font-size: 1.125rem; }

p { margin-bottom: var(--space-md); }

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s;
}
a:hover { color: var(--color-accent-light); text-decoration: underline; }

img { max-width: 100%; height: auto; }

/* --- Utility Classes --- */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 var(--space-lg); }
.text-center { text-align: center; }
.text-muted { color: var(--color-text-muted); }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }

/* --- Top Navigation Bar --- */
.topnav {
  background: var(--color-secondary);
  color: #fff;
  padding: var(--space-sm) 0;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-md);
}
.topnav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.topnav__brand {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  color: #fff;
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  text-decoration: none;
}
.topnav__brand:hover { color: #fff; text-decoration: none; }
.topnav__brand svg { width: 28px; height: 28px; }

.topnav__links { display: flex; gap: var(--space-lg); list-style: none; }
.topnav__links a {
  color: rgba(255,255,255,0.85);
  font-size: 0.9rem;
  font-weight: 500;
  padding: var(--space-xs) 0;
  border-bottom: 2px solid transparent;
  transition: all 0.2s;
}
.topnav__links a:hover,
.topnav__links a.active {
  color: #fff;
  border-bottom-color: var(--color-primary-light);
  text-decoration: none;
}

.topnav__hamburger {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
}

/* --- Hero Section (Landing Page) --- */
.hero {
  background: linear-gradient(135deg, var(--color-secondary) 0%, #1a2a3a 100%);
  color: #fff;
  padding: var(--space-3xl) 0;
  text-align: center;
}
.hero h1 {
  color: #fff;
  font-size: 2.75rem;
  margin-bottom: var(--space-md);
}
.hero p {
  font-size: 1.2rem;
  opacity: 0.9;
  max-width: 700px;
  margin: 0 auto var(--space-xl);
}
.hero__badge {
  display: inline-block;
  background: var(--color-primary);
  color: #fff;
  padding: var(--space-xs) var(--space-md);
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: var(--space-lg);
}
.hero__stats {
  display: flex;
  justify-content: center;
  gap: var(--space-2xl);
  margin-top: var(--space-xl);
}
.hero__stat { text-align: center; }
.hero__stat-number { font-size: 2rem; font-weight: 700; display: block; }
.hero__stat-label { font-size: 0.85rem; opacity: 0.75; }

/* --- Phase Cards (Landing Page) --- */
.phase-section { padding: var(--space-3xl) 0; }
.phase-section h2 { margin-bottom: var(--space-xl); }

.phase-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-lg);
}

.course-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-lg);
  transition: transform 0.2s, box-shadow 0.2s;
  text-decoration: none;
  color: inherit;
  display: block;
}
.course-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  text-decoration: none;
  color: inherit;
}
.course-card__phase-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  margin-bottom: var(--space-sm);
}
.course-card__phase-tag--foundations { background: #FFF3E0; color: #E65100; }
.course-card__phase-tag--som { background: #E3F2FD; color: #1565C0; }
.course-card__phase-tag--pom { background: #F3E5F5; color: #7B1FA2; }
.course-card__phase-tag--clerkship { background: #E8F5E9; color: #2E7D32; }
.course-card__phase-tag--scholarly { background: #FFF8E1; color: #F57F17; }
.course-card__phase-tag--elective { background: #ECEFF1; color: #455A64; }

.course-card h3 {
  font-size: 1.15rem;
  margin-bottom: var(--space-xs);
}
.course-card__code {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-sm);
}
.course-card p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-sm);
}
.course-card__meta {
  display: flex;
  gap: var(--space-md);
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

/* --- Course Page Layout --- */
.course-layout {
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr;
  gap: var(--space-xl);
  padding: var(--space-xl) 0;
}

/* Course Sidebar */
.course-sidebar {
  position: sticky;
  top: 70px;
  height: fit-content;
  max-height: calc(100vh - 90px);
  overflow-y: auto;
}
.course-sidebar__nav { list-style: none; }
.course-sidebar__nav li { margin-bottom: 2px; }
.course-sidebar__nav a {
  display: block;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  transition: all 0.15s;
}
.course-sidebar__nav a:hover {
  background: var(--color-surface-alt);
  color: var(--color-text);
  text-decoration: none;
}
.course-sidebar__nav a.active {
  background: var(--color-primary);
  color: #fff;
}
.course-sidebar__section-title {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  padding: var(--space-sm) var(--space-sm) var(--space-xs);
  font-weight: 600;
}

/* Course Header */
.course-header {
  background: linear-gradient(135deg, var(--color-secondary) 0%, #1a2a3a 100%);
  color: #fff;
  padding: var(--space-2xl) 0;
}
.course-header h1 { color: #fff; margin-bottom: var(--space-xs); }
.course-header__code {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  opacity: 0.7;
  margin-bottom: var(--space-md);
}
.course-header__meta {
  display: flex;
  gap: var(--space-xl);
  flex-wrap: wrap;
}
.course-header__meta-item {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: 0.9rem;
  opacity: 0.85;
}

/* Course Content Sections */
.course-content section {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-xl);
  margin-bottom: var(--space-lg);
}
.course-content section h2 {
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--color-border);
  margin-bottom: var(--space-lg);
}

/* Resource List */
.resource-list { list-style: none; }
.resource-list li {
  padding: var(--space-sm) 0;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: flex-start;
  gap: var(--space-sm);
}
.resource-list li:last-child { border-bottom: none; }
.resource-list__icon {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  margin-top: 2px;
}
.resource-list__tag {
  font-size: 0.7rem;
  padding: 1px 6px;
  border-radius: 3px;
  font-weight: 600;
  margin-left: auto;
  flex-shrink: 0;
}
.resource-list__tag--free { background: #E8F5E9; color: #2E7D32; }
.resource-list__tag--paid { background: #FFF3E0; color: #E65100; }
.resource-list__tag--app { background: #E3F2FD; color: #1565C0; }

/* --- Tabbed Panels (for Lectures / Reading / Problem Sets / Exams) --- */
.tabs {
  display: flex;
  gap: 2px;
  border-bottom: 2px solid var(--color-border);
  margin-bottom: var(--space-lg);
}
.tabs__btn {
  padding: var(--space-sm) var(--space-md);
  border: none;
  background: none;
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-muted);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: all 0.2s;
}
.tabs__btn:hover { color: var(--color-text); }
.tabs__btn.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* --- Flashcard Component --- */
.flashcard-deck {
  display: grid;
  grid-template-columns: 1fr;
  max-width: 600px;
  margin: 0 auto;
}
.flashcard {
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
  min-height: 250px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-xl);
  cursor: pointer;
  transition: transform 0.4s;
  transform-style: preserve-3d;
  position: relative;
}
.flashcard.flipped { transform: rotateY(180deg); }
.flashcard__front, .flashcard__back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-xl);
}
.flashcard__back {
  transform: rotateY(180deg);
  background: var(--color-surface-alt);
  border-radius: var(--radius);
}
.flashcard-controls {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  margin-top: var(--space-md);
}
.flashcard-controls button {
  padding: var(--space-sm) var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  font-family: var(--font-body);
  cursor: pointer;
  transition: all 0.15s;
}
.flashcard-controls button:hover { background: var(--color-surface-alt); }

/* --- Quiz Component --- */
.quiz-container { max-width: 700px; }
.quiz-question {
  background: var(--color-surface-alt);
  border-radius: var(--radius);
  padding: var(--space-lg);
  margin-bottom: var(--space-md);
}
.quiz-question__stem {
  font-weight: 500;
  margin-bottom: var(--space-md);
}
.quiz-question__number {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-sm);
}
.quiz-option {
  display: block;
  width: 100%;
  text-align: left;
  padding: var(--space-sm) var(--space-md);
  margin-bottom: var(--space-xs);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  font-family: var(--font-body);
  font-size: 0.95rem;
  cursor: pointer;
  transition: all 0.15s;
}
.quiz-option:hover { border-color: var(--color-accent); background: #f0fafb; }
.quiz-option.correct { border-color: var(--color-success); background: #E8F5E9; }
.quiz-option.incorrect { border-color: #c62828; background: #FFEBEE; }
.quiz-option.selected { border-color: var(--color-accent); border-width: 2px; }

.quiz-explanation {
  margin-top: var(--space-sm);
  padding: var(--space-md);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  display: none;
}
.quiz-explanation.show { display: block; }
.quiz-explanation.correct-explanation { background: #E8F5E9; border-left: 3px solid var(--color-success); }
.quiz-explanation.incorrect-explanation { background: #FFEBEE; border-left: 3px solid #c62828; }

.quiz-score {
  text-align: center;
  padding: var(--space-xl);
  background: var(--color-surface-alt);
  border-radius: var(--radius);
}
.quiz-score__number { font-size: 2.5rem; font-weight: 700; color: var(--color-primary); }

/* --- Code Runner Component --- */
.code-runner {
  background: #1e1e2e;
  border-radius: var(--radius);
  overflow: hidden;
}
.code-runner__header {
  background: #181825;
  padding: var(--space-sm) var(--space-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.code-runner__title {
  color: #cdd6f4;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}
.code-runner__run-btn {
  background: var(--color-success);
  color: #fff;
  border: none;
  padding: var(--space-xs) var(--space-md);
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}
.code-runner__run-btn:hover { background: #247a4d; }
.code-runner__editor {
  padding: var(--space-md);
  color: #cdd6f4;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.6;
  min-height: 200px;
  overflow-x: auto;
}
.code-runner__editor pre { margin: 0; white-space: pre; }
.code-runner__output {
  background: #11111b;
  padding: var(--space-md);
  color: #a6e3a1;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  border-top: 1px solid #313244;
  min-height: 60px;
  max-height: 300px;
  overflow-y: auto;
}

/* --- Progress Tracker --- */
.progress-bar {
  background: var(--color-border);
  border-radius: 10px;
  height: 8px;
  overflow: hidden;
  margin-bottom: var(--space-sm);
}
.progress-bar__fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-accent), var(--color-success));
  border-radius: 10px;
  transition: width 0.3s ease;
}

.checklist { list-style: none; }
.checklist li {
  padding: var(--space-sm) 0;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  border-bottom: 1px solid var(--color-border);
}
.checklist li:last-child { border-bottom: none; }
.checklist input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--color-primary);
}
.checklist label { cursor: pointer; font-size: 0.95rem; }
.checklist label.completed { text-decoration: line-through; color: var(--color-text-muted); }

/* --- Study Schedule Component --- */
.study-schedule {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 4px;
}
.study-schedule__day {
  text-align: center;
  padding: var(--space-sm);
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
}
.study-schedule__day--active { background: var(--color-accent); color: #fff; }
.study-schedule__day--completed { background: var(--color-success); color: #fff; }
.study-schedule__day--today { border: 2px solid var(--color-primary); }

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 500;
  border: none;
  cursor: pointer;
  transition: all 0.15s;
  text-decoration: none;
}
.btn--primary { background: var(--color-primary); color: #fff; }
.btn--primary:hover { background: var(--color-primary-dark); color: #fff; text-decoration: none; }
.btn--secondary { background: var(--color-surface); border: 1px solid var(--color-border); color: var(--color-text); }
.btn--secondary:hover { background: var(--color-surface-alt); text-decoration: none; }
.btn--accent { background: var(--color-accent); color: #fff; }
.btn--accent:hover { background: var(--color-accent-light); color: #fff; text-decoration: none; }

/* --- Anki Export Button --- */
.anki-export {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  background: #236BFE;
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
}
.anki-export:hover { background: #1a56d4; }

/* --- Footer --- */
.site-footer {
  background: var(--color-secondary);
  color: rgba(255,255,255,0.7);
  padding: var(--space-2xl) 0;
  margin-top: var(--space-3xl);
}
.site-footer a { color: rgba(255,255,255,0.85); }
.site-footer a:hover { color: #fff; }
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-xl);
}
.footer-grid h4 { color: #fff; margin-bottom: var(--space-md); font-size: 0.9rem; }
.footer-grid ul { list-style: none; }
.footer-grid li { margin-bottom: var(--space-sm); font-size: 0.85rem; }
.footer__copyright {
  text-align: center;
  padding-top: var(--space-lg);
  margin-top: var(--space-lg);
  border-top: 1px solid rgba(255,255,255,0.1);
  font-size: 0.8rem;
}

/* --- Responsive --- */
@media (max-width: 900px) {
  .course-layout { grid-template-columns: 1fr; }
  .course-sidebar { display: none; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .hero h1 { font-size: 2rem; }
  .hero__stats { gap: var(--space-lg); }
  .topnav__links { display: none; }
  .topnav__hamburger { display: block; }
  .topnav__links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-secondary);
    padding: var(--space-md);
  }
}

@media (max-width: 600px) {
  .phase-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .hero__stats { flex-direction: column; gap: var(--space-md); }
  .course-header__meta { flex-direction: column; gap: var(--space-sm); }
}