/* ===== Root & Theme ===== */
:root {
  --bg: #0f1115;
  --bg-elev: #141823;
  --text: #e7e9ee;
  --muted: #b8beca;
  --accent: #8aa0ff;
  --card: #121622;
  --ring: #2b3347;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  --radius: 1.25rem;
  --radius-sm: 0.875rem;
  --gap: 1rem;
  --gap-lg: 1.5rem;
  --maxw: 1100px;
  --focus: 0 0 0 3px var(--ring);
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f6f7fb;
    --bg-elev: #ffffff;
    --text: #13151a;
    --muted: #4a5568;
    --accent: #3c6eff;
    --card: #ffffff;
    --ring: #cfd8ff;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
  }
}

html, body {
  height: 100%;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font: 16px/1.55 ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Apple Color Emoji", "Segoe UI Emoji";
  background: radial-gradient(1200px 1200px at 20% -10%, #1a1f2c 0%, var(--bg) 60%) fixed,
              var(--bg);
  color: var(--text);
}

/* ===== Accessibility ===== */
:focus-visible {
  outline: none;
  box-shadow: var(--focus);
  border-radius: var(--radius-sm);
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: -9999px;
}

.skip-link:focus {
  left: 1rem;
  top: 1rem;
  background: var(--bg-elev);
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow);
}

/* ===== Layout ===== */
.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 2rem 1rem 3rem;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: saturate(1.1) blur(6px);
  background: color-mix(in oklab, var(--bg) 70%, transparent);
  border-bottom: 1px solid color-mix(in oklab, var(--ring) 35%, transparent);
}

.site-header .brand,
.site-header .header-actions {
  display: flex;
  align-items: center;
}

.site-header .brand {
  gap: 0.75rem;
  padding: 0.9rem 1rem;
  max-width: var(--maxw);
  margin: 0 auto;
  justify-content: space-between;
}

.site-header .brand h1 {
  font-size: 1.05rem;
  letter-spacing: 0.4px;
  margin: 0;
  color: var(--text);
}

.site-header .dot {
  width: 12px;
  height: 12px;
  border-radius: 999px;
  background: var(--accent);
  box-shadow: 0 0 0 6px color-mix(in oklab, var(--accent) 20%, transparent);
  margin-right: 0.25rem;
}

.header-actions {
  gap: 0.5rem;
}

/* ===== Cards & Tiles ===== */
.card {
  background: linear-gradient(180deg, color-mix(in oklab, var(--card) 88%, transparent), var(--card));
  border: 1px solid color-mix(in oklab, var(--ring) 30%, transparent);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.intro {
  padding: 1.25rem 1.25rem 1.15rem;
  margin-block: 1.25rem 1.75rem;
}

.intro h2 {
  margin: 0 0 0.35rem 0;
  font-size: 1.25rem;
}

.intro p {
  margin: 0;
  color: var(--muted);
}

/* Grid of category tiles */
.grid {
  display: grid;
  gap: var(--gap-lg);
  grid-template-columns: repeat(12, 1fr);
}

.tile {
  grid-column: span 12;
  display: grid;
  grid-template-rows: 1fr auto;
  min-height: 160px;
  padding: 1rem;
  transition: transform 160ms ease, box-shadow 160ms ease, border-color 160ms ease;
}

.tile:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 40px rgba(0, 0, 0, 0.45);
  border-color: color-mix(in oklab, var(--accent) 45%, var(--ring));
}

.tile-body h3 {
  margin: 0 0 0.35rem 0;
  font-size: 1.1rem;
  letter-spacing: 0.2px;
}

.tile-body p {
  margin: 0;
  color: var(--muted);
}

.tile-link {
  margin-top: 1rem;
  justify-self: end;
  text-decoration: none;
  font-weight: 600;
  background: color-mix(in oklab, var(--accent) 24%, var(--bg-elev));
  color: var(--text);
  padding: 0.55rem 0.9rem;
  border-radius: 999px;
  border: 1px solid color-mix(in oklab, var(--accent) 35%, var(--ring));
  transition: transform 160ms ease, background 160ms ease, border-color 160ms ease;
}

.tile-link:hover {
  transform: translateY(-1px);
  background: color-mix(in oklab, var(--accent) 32%, var(--bg-elev));
  border-color: color-mix(in oklab, var(--accent) 60%, var(--ring));
}

/* Responsive columns */
@media (min-width: 600px) {
  .tile { grid-column: span 6; }
}
@media (min-width: 920px) {
  .tile { grid-column: span 3; }
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.5rem 0.8rem;
  background: color-mix(in oklab, var(--accent) 24%, var(--bg-elev));
  color: var(--text);
  border: 1px solid color-mix(in oklab, var(--accent) 35%, var(--ring));
  border-radius: 999px;
  cursor: pointer;
  transition: transform 160ms ease, background 160ms ease, border-color 160ms ease;
}

.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn .icon { font-size: 1rem; }

/* ===== Footer ===== */
.site-footer {
  max-width: var(--maxw);
  margin: 2rem auto 3rem;
  padding: 0 1rem;
  color: var(--muted);
  text-align: center;
}

/* ===== JS toggled themes ===== */
html.theme-light {
  --bg: #f6f7fb;
  --bg-elev: #ffffff;
  --text: #13151a;
  --muted: #4a5568;
  --accent: #3c6eff;
  --card: #ffffff;
  --ring: #cfd8ff;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
  background: radial-gradient(1200px 1200px at 20% -10%, #e8ebff 0%, var(--bg) 60%) fixed,
              var(--bg);
}

/* ===== Utility ===== */
.hidden { display: none !important; }