:root{
  /* Default: light mode */
  --bg0:#f6f7fb;
  --bg1:#eef1f8;
  --card:rgba(10,18,40,.03);
  --text:rgba(12,16,24,.92);
  --muted:rgba(12,16,24,.62);
  --border:rgba(12,16,24,.14);
  /* Site palette (neutral + accessible) */
  --accent:#111827;
  --accent2:#111827;
  --accent3:#111827;
  --shadow:0 10px 24px rgba(10,18,40,.10);
  --radius:18px;
  --glass: rgba(255,255,255,.65);
  --glass2: rgba(255,255,255,.45);
  --hover: rgba(10,18,40,.06);
  --chipBg: rgba(10,18,40,.05);
  --chipSpectrumText: rgba(12,16,24,.90);
  --link: var(--accent2);
  --activeBg: rgba(17,24,39,.10);
  --activeBorder: rgba(17,24,39,.22);
  /* Terminal accents */
  --terminalAmber: #ffb000; /* warm CRT amber */
  --terminalGreen: #39ff14; /* neon green */
  /* Homepage/constellation */
  --canvasSkill: rgba(57, 255, 20, .82);  /* neon green */
  --canvasLang: rgba(0, 200, 255, .86);   /* terminal-cyan (languages) */
  --canvasCourse: rgba(255, 176, 0, .92); /* terminal amber */
  --canvasEdge: rgba(12,16,24,.18);
  --canvasEdgeActive: rgba(57, 255, 20, .42);
  --canvasLabel: rgba(12,16,24,.92);
  --canvasLabelStroke: rgba(255,255,255,.85);
  --btnPrimaryText: #ffffff;
  color-scheme: light;
}

html[data-theme="dark"]{
  --bg0:#0b0f18;
  --bg1:#0b0f18;
  --card:rgba(255,255,255,.05);
  --text:rgba(255,255,255,.92);
  --muted:rgba(255,255,255,.62);
  --border:rgba(255,255,255,.12);
  --accent:#ffffff;
  --accent2:#ffffff;
  --accent3:#ffffff;
  --shadow:0 10px 30px rgba(0,0,0,.35);
  --glass: rgba(0,0,0,.35);
  --glass2: rgba(0,0,0,.22);
  --hover: rgba(255,255,255,.07);
  --chipBg: rgba(255,255,255,.06);
  --chipSpectrumText: rgba(255,255,255,.92);
  --link: var(--accent2);
  --activeBg: rgba(255,255,255,.10);
  --activeBorder: rgba(255,255,255,.18);
  /* Terminal accents */
  --terminalAmber: #ffb000; /* warm CRT amber */
  --terminalGreen: #39ff14; /* neon green */
  /* Homepage/constellation */
  --canvasSkill: rgba(57, 255, 20, .78);  /* neon green */
  --canvasLang: rgba(0, 200, 255, .80);   /* terminal-cyan (languages) */
  --canvasCourse: rgba(255, 176, 0, .88); /* terminal amber */
  --canvasEdge: rgba(255,255,255,.10);
  --canvasEdgeActive: rgba(57, 255, 20, .38);
  --canvasLabel: rgba(255,255,255,.92);
  --canvasLabelStroke: rgba(0,0,0,.55);
  --btnPrimaryText: #050611;
  color-scheme: dark;
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
  background: linear-gradient(180deg, var(--bg0), var(--bg1));
  color:var(--text);
}
a{color:inherit}
.link{color:var(--link);text-decoration:none}
.link:hover{text-decoration:underline}
.container{max-width:1100px;margin:0 auto;padding:28px 18px}
.topbar{
  display:flex;align-items:center;justify-content:space-between;
  gap:12px;padding:14px 16px;border:1px solid var(--border);
  border-radius:999px;background:var(--glass);
}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none}
.brandMark{
  width:28px;height:28px;border-radius:10px;
  background:linear-gradient(135deg,var(--accent),var(--accent2));
  box-shadow:none;
  display:none;
}
.brandText{display:flex;flex-direction:column;gap:6px;line-height:1.0}
.brandText strong{font-size:13px;letter-spacing:.06em;text-transform:uppercase}
.brandText span{font-size:12px;color:var(--muted)}

.themeBtn{
  border:1px solid var(--border);
  background:var(--glass2);
  color:var(--text);
  padding:10px 12px;
  border-radius:999px;
  cursor:pointer;
}
.themeBtn:hover{background:var(--hover)}

/* Round icon-only sun/moon control (Constellation + inner pages) */
.themeBtn.themeFab.themeIconOnly,
.themeToggle.themeIconOnly{
  width: 46px;
  height: 46px;
  padding: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 999px;
  border: 1px solid color-mix(in oklab, var(--border), transparent 22%);
  background: linear-gradient(
    165deg,
    color-mix(in oklab, var(--glass2), rgba(255,255,255,.22) 12%),
    color-mix(in oklab, var(--glass2), rgba(0,0,0,.12) 18%)
  );
  box-shadow:
    0 14px 34px rgba(0,0,0,.12),
    inset 0 1px 0 rgba(255,255,255,.18);
  color: var(--text);
}
.themeBtn.themeFab.themeIconOnly:hover,
.themeToggle.themeIconOnly:hover{
  background: var(--hover);
  transform: translateY(-1px);
  box-shadow:
    0 18px 40px rgba(0,0,0,.14),
    inset 0 1px 0 rgba(255,255,255,.20);
}
/*
 * Theme glyphs: external SVG as <img> cannot resolve currentColor from the page.
 * Mask + background-color: currentColor tints the icon from the button’s color.
 */
.themeIconOnly .themeGlyph{
  display: block;
  width: 22px;
  height: 22px;
  flex-shrink: 0;
  background-color: currentColor;
  mask-type: alpha;
  -webkit-mask-size: contain;
  mask-size: contain;
  -webkit-mask-repeat: no-repeat;
  mask-repeat: no-repeat;
  -webkit-mask-position: center;
  mask-position: center;
}
.themeIconOnly .themeGlyph--moon{
  -webkit-mask-image: url("theme-moon.svg");
  mask-image: url("theme-moon.svg");
}
.themeIconOnly .themeGlyph--sun{
  -webkit-mask-image: url("theme-sun.svg");
  mask-image: url("theme-sun.svg");
}
html[data-theme="light"] .themeIconOnly .themeGlyph--sun{ display: none; }
html[data-theme="dark"] .themeIconOnly .themeGlyph--moon{ display: none; }

@media (prefers-reduced-motion: reduce){
  .themeBtn.themeFab.themeIconOnly:hover,
  .themeToggle.themeIconOnly:hover{ transform: none; }
}

.nav{display:flex;gap:10px;flex-wrap:wrap}
.pill{
  display:inline-flex;align-items:center;gap:8px;
  padding:10px 12px;border-radius:999px;text-decoration:none;
  border:1px solid var(--border);background:var(--glass2);
}
.pill:hover{background:var(--hover)}
.hero{padding:36px 0 18px}
.hero h1{margin:14px 0 8px;font-size:42px;letter-spacing:-.02em}
.hero p{margin:0;color:var(--muted);max-width:70ch;font-size:16px;line-height:1.6}
.grid{display:grid;gap:14px}
.grid.cards{grid-template-columns:repeat(12,1fr)}
.card{
  border:1px solid var(--border);
  background:var(--glass2);
  border-radius:var(--radius);
  box-shadow:var(--shadow);
  overflow:hidden;
}
.cardInner{padding:16px}
.kicker{font-size:12px;color:var(--muted);letter-spacing:.08em;text-transform:uppercase}
.h2{font-size:22px;margin:6px 0 8px}
.btn{
  cursor:pointer;
  display:inline-flex;align-items:center;gap:8px;
  padding:10px 12px;border-radius:999px;
  border:1px solid var(--border);
  background:var(--glass2);color:var(--text);
  text-decoration:none;
}
.btn:hover{background:var(--hover)}
.btn:focus-visible,
.pill:focus-visible,
.chip:focus-visible,
.modalClose:focus-visible{
  outline: 2px solid rgba(0,0,0,.72);
  outline-offset: 3px;
}
html[data-theme="dark"] .btn:focus-visible,
html[data-theme="dark"] .pill:focus-visible,
html[data-theme="dark"] .chip:focus-visible,
html[data-theme="dark"] .modalClose:focus-visible{
  outline: 2px solid rgba(255,255,255,.78);
}

@media (prefers-reduced-motion: reduce){
  *{scroll-behavior:auto !important}
  .courseCard{transition:none !important}
  .btn.primary:hover{filter:none !important}
}
.btn.primary{
  border-color:transparent;
  background:linear-gradient(135deg,var(--accent),var(--accent2));
  color:var(--btnPrimaryText);
}
.btn.primary:hover{filter:brightness(1.06)}
.chips{display:flex;gap:8px;flex-wrap:wrap}
.chip{
  padding:8px 10px;border-radius:999px;border:1px solid var(--border);
  background:var(--chipBg);color:var(--muted);font-size:12px;
  white-space: nowrap;
}
button.chip{
  font:inherit;
  cursor:pointer;
  appearance:none;
  text-align:left;
}
.chip[data-active="true"]{
  color:var(--text);
  background:var(--activeBg);
  border-color:var(--activeBorder);
  /* Make active filters unambiguous even when chips have inline colors */
  outline: 2px solid rgba(0,0,0,.70);
  outline-offset: 2px;
  box-shadow: 0 0 0 2px rgba(0,0,0,.65), 0 14px 36px rgba(0,0,0,.18) !important;
  font-weight: 700;
}
html[data-theme="dark"] .chip[data-active="true"]{
  outline: 2px solid rgba(255,255,255,.78);
  box-shadow: 0 0 0 2px rgba(255,255,255,.65), 0 18px 44px rgba(0,0,0,.35) !important;
}
.chip[data-active="true"]::before{
  content: "✓";
  display: inline-block;
  margin-right: 6px;
  opacity: .9;
}

.themeFab{
  position: fixed;
  right: max(16px, env(safe-area-inset-right, 0px));
  bottom: max(16px, env(safe-area-inset-bottom, 0px));
  z-index: 50;
}
.sectionTitle{margin:22px 0 10px;font-size:18px}
.courseCard{grid-column:span 4;min-height:188px;position:relative;cursor:pointer}
.courseCard:hover{transform:translateY(-2px)}
.courseCard{transition:transform .14s ease}
.courseMeta{display:flex;gap:10px;flex-wrap:wrap}
.courseCode{font-weight:700}
.muted{color:var(--muted)}
.footer{padding:26px 0 40px;color:var(--muted);font-size:13px}

/* Modal */
.backdrop{
  position:fixed;inset:0;background:rgba(0,0,0,.55);
  backdrop-filter: blur(6px);
  display:none;align-items:center;justify-content:center;
  padding:16px;
}
.backdrop[data-open="true"]{display:flex}
.modal{
  width:min(860px, calc(100vw - 26px));
  border-radius:22px;border:1px solid var(--border);
  background:var(--glass);
  box-shadow:0 40px 120px rgba(0,0,0,.35);
}
.modalHead{display:flex;align-items:flex-start;justify-content:space-between;gap:10px;padding:18px 18px 0}
.modalBody{padding:0 18px 18px}
.modalClose{border:none;background:transparent;color:var(--muted);font-size:18px;cursor:pointer;padding:6px 10px;border-radius:10px}
.modalClose:hover{background:rgba(255,255,255,.06);color:var(--text)}

details summary{list-style:none}
details summary::-webkit-details-marker{display:none}

@media (max-width: 900px){
  .hero h1{font-size:34px}
  .courseCard{grid-column:span 6}
}
@media (max-width: 560px){
  .topbar{border-radius:18px}
  .courseCard{grid-column:span 12}
}