/* ============================================================
   10 Multimedia 2026 - Teaching Hub Stylesheet
   Written by: Yunshu Gao, April 2026
   This stylesheet itself is a teaching artefact - students can
   and should read it to see real-world CSS patterns.
   ============================================================ */

:root {
  --c-navy: #1f3a68;
  --c-navy-light: #2e5b9e;
  --c-teal: #14b8a6;
  --c-teal-dark: #0f766e;
  --c-bg: #fafbfc;
  --c-surface: #ffffff;
  --c-border: #e4e7ec;
  --c-text: #1a202c;
  --c-text-soft: #4a5568;
  --c-code-bg: #0d1117;
  --c-code-text: #e6edf3;
  --c-warn: #f59e0b;
  --c-success: #10b981;
  --c-error: #ef4444;

  --font-body: "Inter", system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
  --font-head: "Inter", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", Consolas, Monaco, "Courier New", monospace;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, .06);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, .08);
  --shadow-lg: 0 12px 40px rgba(0, 0, 0, .12);

  --container: 1100px;
  --gutter: clamp(1rem, 3vw, 2rem);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--c-text);
  background: var(--c-bg);
  line-height: 1.6;
  font-size: 16px;
}

a { color: var(--c-navy-light); text-decoration: none; font-weight: 500; }
a:hover { text-decoration: underline; color: var(--c-navy); }

h1, h2, h3, h4 { font-family: var(--font-head); color: var(--c-navy); line-height: 1.2; margin-top: 2rem; }
h1 { font-size: clamp(1.8rem, 4vw, 2.6rem); margin-top: 0; }
h2 { font-size: clamp(1.4rem, 3vw, 1.9rem); border-bottom: 2px solid var(--c-border); padding-bottom: .4rem; }
h3 { font-size: 1.25rem; }

code { font-family: var(--font-mono); background: #f3f4f6; color: #111; padding: .15em .4em; border-radius: 4px; font-size: .92em; }
pre {
  background: var(--c-code-bg); color: var(--c-code-text);
  padding: 1rem 1.25rem; border-radius: var(--radius-md); overflow-x: auto;
  font-family: var(--font-mono); font-size: .9rem; line-height: 1.55;
  margin: 1rem 0;
}
pre code { background: transparent; color: inherit; padding: 0; }

/* Site header */
.site-header {
  background: linear-gradient(135deg, var(--c-navy) 0%, var(--c-navy-light) 100%);
  color: white; padding: 1rem var(--gutter);
  position: sticky; top: 0; z-index: 50; box-shadow: var(--shadow-md);
}
.site-header-inner {
  max-width: var(--container); margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  flex-wrap: wrap;
}
.site-header a { color: white; text-decoration: none; }
.site-brand { font-weight: 700; font-size: 1.1rem; }
.site-nav { display: flex; gap: 1.25rem; font-size: .95rem; flex-wrap: wrap; }
.site-nav a:hover { text-decoration: underline; }

/* Layout containers */
.container { max-width: var(--container); margin: 0 auto; padding: 2rem var(--gutter); }
.hero { padding: 3rem var(--gutter) 2rem; text-align: center; }
.hero h1 { color: var(--c-navy); }
.hero .lead { font-size: 1.15rem; color: var(--c-text-soft); max-width: 700px; margin: 1rem auto; }

/* Cards & grids */
.card {
  background: var(--c-surface); border: 1px solid var(--c-border);
  border-radius: var(--radius-lg); padding: 1.5rem; box-shadow: var(--shadow-sm);
  transition: transform .15s ease, box-shadow .15s ease;
}
.card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.card h3 { margin-top: 0; }
.card .meta { font-size: .85rem; color: var(--c-text-soft); margin-bottom: .5rem; }

.grid { display: grid; gap: 1.25rem; }
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); }

/* Lesson card specific */
.lesson-card {
  display: block; padding: 1.25rem; background: var(--c-surface);
  border: 1px solid var(--c-border); border-radius: var(--radius-md);
  border-left: 4px solid var(--c-teal);
  color: var(--c-text); text-decoration: none;
  transition: all .15s ease;
}
.lesson-card:hover { text-decoration: none; border-left-color: var(--c-navy); box-shadow: var(--shadow-md); transform: translateX(2px); }
.lesson-card .lesson-id { font-family: var(--font-mono); font-size: .8rem; color: var(--c-teal-dark); font-weight: 600; }
.lesson-card .lesson-title { font-weight: 600; font-size: 1.05rem; color: var(--c-navy); margin: .25rem 0; }
.lesson-card .lesson-desc { font-size: .9rem; color: var(--c-text-soft); }

/* Buttons */
.btn {
  display: inline-block; padding: .6rem 1.2rem; background: var(--c-navy); color: white;
  border-radius: var(--radius-sm); font-weight: 500; text-decoration: none;
  border: none; cursor: pointer; font-size: .95rem;
}
.btn:hover { background: var(--c-navy-light); text-decoration: none; color: white; }
.btn-teal { background: var(--c-teal); }
.btn-teal:hover { background: var(--c-teal-dark); }
.btn-outline { background: transparent; color: var(--c-navy); border: 2px solid var(--c-navy); }
.btn-outline:hover { background: var(--c-navy); color: white; }

/* Callouts */
.callout {
  padding: 1rem 1.25rem; border-radius: var(--radius-md);
  border-left: 4px solid var(--c-teal); background: #f0fdfa;
  margin: 1.5rem 0;
}
.callout.warn { border-color: var(--c-warn); background: #fffbeb; }
.callout.info { border-color: var(--c-navy-light); background: #eff6ff; }
.callout.success { border-color: var(--c-success); background: #ecfdf5; }
.callout strong { color: var(--c-navy); }

/* Lesson page structure */
.lesson-head {
  background: linear-gradient(135deg, #eff6ff 0%, #f0fdfa 100%);
  padding: 2rem var(--gutter); border-bottom: 1px solid var(--c-border);
}
.lesson-head .lesson-pill {
  display: inline-block; background: var(--c-teal); color: white;
  padding: .3rem .8rem; border-radius: 999px; font-size: .85rem; font-weight: 600;
}
.lesson-head h1 { margin: .75rem 0; color: var(--c-navy); }
.lesson-head .lesson-meta { color: var(--c-text-soft); font-size: .95rem; }

.lesson-section {
  background: var(--c-surface); border: 1px solid var(--c-border);
  border-radius: var(--radius-md); padding: 1.5rem; margin-bottom: 1.5rem;
}
.lesson-section h2 {
  margin-top: 0; font-size: 1.3rem; color: var(--c-navy);
  border: 0; padding: 0;
  display: flex; align-items: center; gap: .6rem;
}
.section-badge {
  font-size: .75rem; padding: .2rem .5rem; border-radius: 4px;
  background: var(--c-teal); color: white; font-weight: 500;
}

.tier-grid { display: grid; gap: 1rem; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }
.tier { padding: 1rem; border-radius: var(--radius-sm); border-top: 3px solid; background: #fafbfc; }
.tier.support { border-color: #8b5cf6; }
.tier.core { border-color: var(--c-teal); }
.tier.extension { border-color: #f59e0b; }
.tier h4 { margin: 0 0 .5rem; color: var(--c-navy); font-size: .95rem; text-transform: uppercase; letter-spacing: .05em; }

/* Lesson navigation */
.lesson-nav {
  display: flex; justify-content: space-between; gap: 1rem;
  margin-top: 2rem; padding-top: 2rem; border-top: 1px solid var(--c-border);
}
.lesson-nav a {
  padding: .75rem 1rem; background: var(--c-surface); border: 1px solid var(--c-border);
  border-radius: var(--radius-sm); color: var(--c-navy); font-weight: 500;
  flex: 1; max-width: 45%;
}
.lesson-nav a.prev::before { content: "← "; }
.lesson-nav a.next { text-align: right; }
.lesson-nav a.next::after { content: " →"; }
.lesson-nav a.disabled { opacity: .4; pointer-events: none; }

/* Outcome tags */
.outcomes { display: flex; flex-wrap: wrap; gap: .4rem; margin: .5rem 0 1rem; }
.outcome-tag {
  padding: .2rem .55rem; background: #e0e7ff; color: #3730a3;
  border-radius: 4px; font-size: .8rem; font-family: var(--font-mono);
}

/* Worksheet zone */
.worksheet { background: #fffbeb; border: 2px dashed var(--c-warn); padding: 1.25rem; border-radius: var(--radius-md); margin: 1rem 0; }
.worksheet h3 { color: #92400e; margin-top: 0; }

/* Footer */
.site-footer {
  background: var(--c-navy); color: #cbd5e1;
  padding: 2.5rem var(--gutter); margin-top: 4rem; text-align: center;
  font-size: .9rem;
}
.site-footer a { color: #93c5fd; }

/* Print adjustments */
@media print {
  .site-header, .site-footer, .lesson-nav, .no-print { display: none !important; }
  body { background: white; color: black; }
  .lesson-section { box-shadow: none; border: 1px solid #ccc; break-inside: avoid; }
}

/* Responsive */
@media (max-width: 640px) {
  .site-header-inner { flex-direction: column; align-items: flex-start; }
  h1 { font-size: 1.6rem; }
  .lesson-nav { flex-direction: column; }
  .lesson-nav a { max-width: 100%; }
}