/* ==========================================================================
   Variables & Root
   ========================================================================== */
:root {
  /* Colors */
  --color-primary: #1e3a8a; /* Deep UdeS-like blue */
  --color-primary-dark: #1e40af;
  --color-primary-light: #dbeafe;
  --color-text-main: #334155;
  --color-text-muted: #64748b;
  --color-text-light: #f8fafc;
  --color-bg-main: #ffffff;
  --color-bg-off: #f1f5f9;
  --color-border: #e2e8f0;
  
  /* Typography */
  --font-family-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-size-base: 16px;
  --line-height-base: 1.6;
  
  /* Layout */
  --max-width: 1200px;
  --max-width-narrow: 800px;
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 4rem;
  --spacing-xl: 6rem;
  
  /* Misc */
  --border-radius: 8px;
  --border-radius-lg: 12px;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --transition-speed: 0.4s cubic-bezier(0.165, 0.84, 0.44, 1);
  --transition-reveal: 0.7s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

/* ==========================================================================
   Reset & Base Details
   ========================================================================== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-family: var(--font-family-sans);
  font-size: var(--font-size-base);
  line-height: var(--line-height-base);
  color: var(--color-text-main);
  background-color: var(--color-bg-main);
  scroll-behavior: smooth;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 12px;
}

::-webkit-scrollbar-track {
  background: var(--color-bg-main);
}

::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 10px;
  border: 3px solid var(--color-bg-main);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-primary);
}

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

a:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.nav-brand:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 4px;
}

.nav-menu a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.btn-action:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.footer a:focus-visible {
  outline: 2px solid var(--color-primary-light);
  outline-offset: 2px;
}

img, iframe {
  max-width: 100%;
  border-radius: var(--border-radius);
  display: block;
}

iframe {
  border: 0;
}

/* ==========================================================================
   Typography
   ========================================================================== */
h1, h2, h3, h4, h5, h6 {
  color: #0f172a;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--spacing-sm);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; margin-top: var(--spacing-lg); }
h3 { font-size: 1.5rem; }

p, ul, ol {
  margin-bottom: var(--spacing-sm);
}

.lead {
  font-size: 1.15rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

ul, ol {
  padding-left: var(--spacing-md);
}

/* ==========================================================================
   Layout Containers
   ========================================================================== */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-sm);
}

.container-narrow {
  max-width: var(--max-width-narrow);
}

.section {
  padding: var(--spacing-lg) 0;
}

.section-bg {
  background: linear-gradient(180deg, var(--color-bg-off) 0%, var(--color-bg-main) 100%);
}

/* ==========================================================================
   Content Cards — Universal content container (Apple-inspired)
   ========================================================================== */
.content-card {
  background: white;
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-md);
  box-shadow: var(--shadow-md);
  margin-bottom: var(--spacing-md);
}

.content-card h2 {
  margin-top: 0;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--color-border);
}

.content-card h3 {
  margin-top: 0;
}

.content-card > *:last-child {
  margin-bottom: 0;
}

/* Section Title — Standalone heading that animates before a grid */
.section-title {
  margin-bottom: var(--spacing-md);
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--color-border);
}

/* ==========================================================================
   Navigation
   ========================================================================== */
.navbar {
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 1000;
  box-shadow: var(--shadow-sm);
}

.navbar .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 60px;
}

.nav-brand {
  font-size: 1.25rem;
  font-weight: 700;
  color: #0f172a;
}

.nav-brand span {
  color: var(--color-primary);
}

.nav-menu {
  display: flex;
  gap: var(--spacing-md);
  list-style: none;
  padding: 0;
  margin: 0;
}

.nav-item a {
  color: var(--color-text-main);
  font-weight: 500;
}

.nav-item a:hover,
.nav-item a.active {
  text-decoration: none;
  color: var(--color-primary);
}

.nav-utilities {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin-left: var(--spacing-md);
  font-size: 0.82rem;
  color: var(--color-text-muted);
  white-space: nowrap;
}

.nav-utilities a {
  color: var(--color-text-muted);
  font-weight: 600;
  text-decoration: none;
}

.nav-utilities a:hover {
  color: var(--color-primary);
  text-decoration: none;
}

/* Mobile Menu Checkbox Hack */
.nav-toggle-input {
  display: none;
}

.nav-toggle-label {
  display: none;
  cursor: pointer;
  padding: 10px;
}

.nav-toggle-label span {
  display: block;
  width: 25px;
  height: 3px;
  background-color: var(--color-text-main);
  margin-bottom: 5px;
  border-radius: 3px;
}

@media (max-width: 768px) {
  .nav-toggle-label {
    display: block;
  }

  .nav-utilities {
    display: none;
  }
  
  .nav-menu {
    position: absolute;
    top: 60px;
    left: 0;
    width: 100%;
    background-color: white;
    flex-direction: column;
    gap: 0;
    display: none;
    box-shadow: var(--shadow-md);
  }
  
  .nav-item {
    width: 100%;
    border-top: 1px solid var(--color-border);
  }
  
  .nav-item a {
    display: block;
    padding: var(--spacing-sm);
    text-align: center;
  }

  .nav-toggle-input:checked ~ .nav-menu {
    display: flex;
  }
}

/* ==========================================================================
   Hero Header
   ========================================================================== */
.hero {
  position: relative;
  height: 60vh;
  min-height: 400px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-top: 60px; /* Offset for navbar */
  overflow: hidden;
  background-color: #0f172a; /* Fallback */
}

.hero--sub {
  height: 40vh;
  min-height: 300px;
}

.hero--detail {
  height: 35vh;
  min-height: 250px;
}

.hero--detail .hero-content h1 {
  font-size: 2.5rem;
  margin-bottom: 0;
}

/* 1.2s duration: keep in mind when tuning js/animations.js FIRST_MAIN_DELAY_MS (~1050) */
.hero-img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: 1;
  filter: brightness(0.6);
  animation: heroImgReveal 1.2s cubic-bezier(0.165, 0.84, 0.44, 1) forwards;
  opacity: 0;
}

.hero-content {
  position: relative;
  z-index: 10;
  text-align: center;
  color: white;
  padding: var(--spacing-md);
}

/* Hero copy: load-only keyframes (no JS); image uses heroImgReveal below */
.hero-content h1 {
  color: white;
  font-size: 3rem;
  margin-bottom: var(--spacing-sm);
  text-shadow: 0 2px 10px rgba(0,0,0,0.3);
  opacity: 0;
  transform: translateY(14px);
  animation: heroTextReveal 0.72s cubic-bezier(0.25, 0.46, 0.45, 0.94) forwards;
  animation-delay: 0.18s;
}

.hero-content p {
  opacity: 0;
  transform: translateY(14px);
  animation: heroTextReveal 0.72s cubic-bezier(0.25, 0.46, 0.45, 0.94) forwards;
  animation-delay: 0.78s;
}

@keyframes heroTextReveal {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (prefers-reduced-motion: reduce) {
  .hero-img,
  .hero-content h1,
  .hero-content p {
    animation: none;
    opacity: 1;
    transform: none;
  }
}

@keyframes heroImgReveal {
  from {
    opacity: 0;
    transform: scale(1.1);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

/* ==========================================================================
   Grid & Cards (Projects, Resources)
   ========================================================================== */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--spacing-md);
  margin-top: var(--spacing-md);
}

.card {
  background: white;
  border-radius: var(--border-radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-speed), box-shadow var(--transition-speed);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.card-img-wrapper {
  position: relative;
  height: 200px;
  overflow: hidden;
}

.card-img-wrapper img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-speed);
}

.card:hover .card-img-wrapper img {
  transform: scale(1.05);
}

/* Responsive 16:9 YouTube (and similar) inside resource cards */
.card-img-wrapper.card-img-wrapper--video-embed {
  height: auto;
  aspect-ratio: 16 / 9;
  max-height: none;
}

.card-img-wrapper.card-img-wrapper--video-embed iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
  border-radius: var(--border-radius) var(--border-radius) 0 0;
}

/* Logos / placeholders until a cover thumbnail exists (same box as project cards) */
.card-img-wrapper.card-img-wrapper--contain {
  background: var(--color-bg-off);
}

.card-img-wrapper.card-img-wrapper--contain img {
  object-fit: contain;
  object-position: center;
  padding: 1rem;
}

.card-title {
  padding: var(--spacing-sm);
  background: white;
  border-top: 1px solid var(--color-border);
  flex-grow: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  height: 60px; /* Fixed height for title area for grid alignment */
  color: #0f172a;
  font-weight: 700;
  font-size: 0.95rem;
  line-height: 1.3;
}

.card-title a {
  color: #0f172a;
  font-weight: 700;
  font-size: 0.95rem;
  line-height: 1.3;
  transition: color var(--transition-speed);
}

.card-title a:hover {
  color: var(--color-primary);
  text-decoration: none;
}

.card-content {
  padding: var(--spacing-sm);
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.card-content > *:last-child {
  margin-bottom: 0;
}

.resource-card .card-title a {
  display: block;
  padding: 0.125rem 0.35rem;
}

/* Specific Resource Cards (like YouTube / PDFs) */
.resource-card iframe {
  width: 100%;
  border-radius: var(--border-radius) var(--border-radius) 0 0;
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
  background-color: #0f172a;
  color: var(--color-text-light);
  padding: var(--spacing-md) 0;
  text-align: center;
  margin-top: auto;
}

.footer a {
  color: var(--color-primary-light);
}

.footer a:hover {
  color: white;
}

/* ==========================================================================
   Utility Classes
   ========================================================================== */
.text-center { text-align: center; }
.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-4 { margin-bottom: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-md); }

/* Colab: intro + category headings use the same card grids as projects */
#colab .container-narrow {
  margin-bottom: var(--spacing-md);
}

#colab h3.section-title {
  margin-top: var(--spacing-lg);
}

#colab .container-narrow + h3.section-title {
  margin-top: 0;
}

/* ==========================================================================
   Project Pages Specific
   ========================================================================== */
.project-container {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

@media (min-width: 900px) {
  .project-container {
    flex-direction: row;
    align-items: flex-start;
  }
}

.project-main {
  flex: 3;
}

.project-sidebar {
  flex: 1;
  background-color: var(--color-bg-off);
  padding: var(--spacing-sm);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 80px;
}

.project-meta-item {
  margin-bottom: var(--spacing-sm);
  padding-bottom: var(--spacing-sm);
  border-bottom: 1px solid var(--color-border);
}

.project-meta-item:last-child {
  border-bottom: none;
  margin-bottom: 0;
  padding-bottom: 0;
}

.project-meta-label {
  font-size: 0.85rem;
  text-transform: uppercase;
  color: var(--color-text-muted);
  font-weight: 700;
  letter-spacing: 0.05em;
  margin-bottom: 0.25rem;
}

.project-meta-value {
  font-weight: 500;
  color: var(--color-text-main);
}

/* Partner row: optional logo(s) + caption (project sidebar) */
.project-meta-partner {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.project-partner-logos {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  width: 100%;
}

.project-partner-logo-link {
  display: block;
  flex: 1 1 calc(50% - 0.375rem);
  max-width: calc(50% - 0.375rem);
  min-width: 0;
  width: auto;
  text-decoration: none;
}

.project-partner-logos > .project-partner-logo-link:only-of-type {
  flex: none;
  width: 100%;
  max-width: 100%;
}

.project-partner-logo {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  max-height: 88px;
  object-fit: contain;
  object-position: left center;
}

/* Multiple imgs in one strip: each scales within its flex cell */
.project-partner-logos .project-partner-logo:not(:only-child) {
  flex: 1 1 calc(50% - 0.375rem);
  width: auto;
  max-width: calc(50% - 0.375rem);
  min-width: 0;
}

.project-partner-names {
  font-size: 0.9rem;
  line-height: 1.35;
}

/* ==========================================================================
   Action Buttons (Option A)
   ========================================================================== */
.action-links-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}

.btn-action {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background-color: var(--color-bg-off);
  color: var(--color-text-main);
  padding: 0.5rem 1rem;
  border-radius: 9999px; /* Pill shape */
  font-size: 0.9rem;
  font-weight: 600;
  border: 1px solid var(--color-border);
  transition: all var(--transition-speed);
}

.btn-action:hover {
  background-color: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

/* ==========================================================================
   Project Citation Box
   ========================================================================== */
.citation-box {
  background-color: var(--color-bg-off);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--border-radius);
  padding: var(--spacing-sm) var(--spacing-md);
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.85rem;
  overflow-x: auto;
  white-space: pre-wrap;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-md);
}

/* Adjusted for long bibliography links */
.action-links-row .btn-action {
  text-align: left;
  line-height: 1.4;
  height: auto;
  white-space: normal;
}

/* ==========================================================================
   Teaching & Syllabus
   ========================================================================== */
.syllabus-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  margin: var(--spacing-md) 0;
  font-size: 0.95rem;
  border: none;
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
}

.syllabus-table th {
  background: var(--color-bg-off);
  color: var(--color-text-main);
  text-align: left;
  padding: var(--spacing-sm);
  border-bottom: 2px solid var(--color-border);
  font-weight: 700;
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 0.05em;
}

.syllabus-table td {
  padding: var(--spacing-sm);
  border-bottom: 1px solid var(--color-border);
  vertical-align: top;
  background: white;
}

.syllabus-table tr:last-child td {
  border-bottom: none;
}

.syllabus-week {
  font-weight: 700;
  color: var(--color-primary);
  width: 120px;
}

.syllabus-topic h4 {
  margin: 0 0 var(--spacing-xs) 0;
  color: var(--color-text-main);
  font-size: 1.1rem;
}

.syllabus-topic p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.syllabus-resources ul {
  margin: 0;
  padding-left: 1.2rem;
  font-size: 0.9rem;
}

.logistics-card {
  background: var(--color-bg-off);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-md);
}

.logistics-card h3 {
  margin-top: 0;
  border-bottom: 1px solid var(--color-border);
  padding-bottom: var(--spacing-xs);
  margin-bottom: var(--spacing-sm);
  font-size: 1.2rem;
}

.logistics-item {
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.5rem;
  font-size: 0.9rem;
  gap: var(--spacing-sm);
}

.logistics-label {
  font-weight: 600;
  color: var(--color-text-muted);
  flex-shrink: 0;
}

.logistics-value {
  text-align: right;
  color: var(--color-text-main);
}

.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
}

.badge-due { background: rgba(231, 76, 60, 0.1); color: #e74c3c; }
.badge-done { background: rgba(46, 204, 113, 0.1); color: #2ecc71; }

/* 
   ==========================================================================
   Animations (scroll reveal + first-section load)
   ==========================================================================
   Overview:
   - Hero text: keyframes above (.hero-content h1/p) — no .reveal, no animations.js.
   - Main/footer: animations.js adds .reveal then .revealed (scroll IO or first-section timeout).
   - Pre-JS block below: same opacity as .reveal for first main section only (listing pages),
     so content does not flash visible then hide. See agent.md "Page load & scroll animations".
   ==========================================================================
*/

/*
 * Pre-JS hiding: match .reveal opacity before JS to avoid a full-opacity flash.
 * :not(.reveal) stops applying once JS adds .reveal.
 *
 * Block A — Listing pages (no .project-container): titles, cards, grids, etc.
 * Block B — Project/course pages (.project-container): content-cards + sidebar.
 */
main > section:first-of-type:not(:has(.project-container)) :is(
  .container > .section-title:not(.reveal),
  .content-card:not(.reveal),
  .grid .card:not(.reveal),
  .container > p:not(.reveal),
  .container-narrow > div:not(.grid):not(.content-card):not(.reveal),
  .container > div:has(> h2.section-title):not(.grid):not(.reveal),
  .container > div:has(> h3.section-title):not(.grid):not(.reveal)
) {
  opacity: 0;
  transform: translateY(24px);
}

.project-container :is(
  .content-card:not(.reveal),
  .project-sidebar:not(.reveal),
  .project-main > div:not(.content-card):not(.reveal),
  .project-main > .section-title:not(.reveal)
) {
  opacity: 0;
  transform: translateY(24px);
}

@media (prefers-reduced-motion: reduce) {
  main > section:first-of-type:not(:has(.project-container)) :is(
    .container > .section-title:not(.reveal),
    .content-card:not(.reveal),
    .grid .card:not(.reveal),
    .container > p:not(.reveal),
    .container-narrow > div:not(.grid):not(.content-card):not(.reveal),
    .container > div:has(> h2.section-title):not(.grid):not(.reveal),
    .container > div:has(> h3.section-title):not(.grid):not(.reveal)
  ) {
    opacity: 1;
    transform: none;
  }

  .project-container :is(
    .content-card:not(.reveal),
    .project-sidebar:not(.reveal),
    .project-main > div:not(.content-card):not(.reveal),
    .project-main > .section-title:not(.reveal)
  ) {
    opacity: 1;
    transform: none;
  }
}

/* .reveal = hidden; .reveal.revealed = visible (JS adds .revealed after scroll or load timeout). */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity var(--transition-reveal),
              transform var(--transition-reveal);
  transition-delay: 0s; /* JS sets per-element for grid stagger */
  will-change: opacity, transform;
}

.reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* If scripts are disabled, .reveal is never applied — default visible layout (progressive enhancement). */
@media (prefers-reduced-motion: reduce) {
  /* Skip motion on scroll-reveal targets; hero copy also resets above. */
  .reveal {
    transition: none;
    opacity: 1;
    transform: none;
  }
}