/* Theme variables */
:root {
  --bg: #f8fafc;
  --text: #0f172a;
  --muted: #64748b;
  --subtle: #475569;
  --border: #e5e7eb;
  --hover-bg: #f1f5f9;
  --header-bg: #ffffff;
  --nav-bg: #ffffff;
  --card-bg: #ffffff;
  --footer-bg: #ffffff;
  --link: #334155;
  --shadow: rgba(15, 23, 42, 0.06);
}

[data-theme="dark"] {
  --bg: #0b1220;
  --text: #e5e7eb;
  --muted: #94a3b8;
  --subtle: #94a3b8;
  --border: #1f2a44;
  --hover-bg: rgba(148, 163, 184, 0.12);
  --header-bg: #0f172a;
  --nav-bg: #0f172a;
  --card-bg: #111827;
  --footer-bg: #0f172a;
  --link: #cbd5e1;
  --shadow: rgba(0, 0, 0, 0.5);
}

/* Respect system preference when no explicit choice */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --bg: #0b1220;
    --text: #e5e7eb;
    --muted: #94a3b8;
    --subtle: #94a3b8;
    --border: #1f2a44;
    --hover-bg: rgba(148, 163, 184, 0.12);
    --header-bg: #0f172a;
    --nav-bg: #0f172a;
    --card-bg: #111827;
    --footer-bg: #0f172a;
    --link: #cbd5e1;
    --shadow: rgba(0, 0, 0, 0.5);
  }
}

/* Reset & base */
* { margin: 0; padding: 0; box-sizing: border-box; }

html, body { height: 100%; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.65;
  display: flex;
  flex-direction: column;
}

.container { max-width: 960px; margin: 0 auto; padding: 0 1rem; }

/* Header */
.site-header { background-color: var(--header-bg); border-bottom: 1px solid var(--border); }
.header-inner { padding: 2rem 0 1rem; text-align: center; }
.site-title { font-size: 1.75rem; font-weight: 700; letter-spacing: -0.01em; }
.site-tagline { margin-top: 0.25rem; color: var(--subtle); font-size: 0.95rem; }

/* Nav */
.site-nav { background-color: var(--nav-bg); }
.nav-list { list-style: none; display: flex; gap: 0.75rem; padding: 0.5rem 0 0.75rem; flex-wrap: wrap; justify-content: center; }
.nav-link { color: var(--link); text-decoration: none; padding: 0.5rem 0.75rem; border-radius: 0.5rem; font-weight: 500; }
.nav-link:hover, .nav-link:focus { background-color: var(--hover-bg); outline: none; }

/* Theme toggle */
.theme-toggle {
  border: 1px solid var(--border);
  background: transparent;
  color: var(--link);
  padding: 0.5rem 0.75rem;
  border-radius: 0.5rem;
  font-weight: 500;
  cursor: pointer;
}
.theme-toggle:hover, .theme-toggle:focus {
  background-color: var(--hover-bg);
  outline: none;
}

/* Sections */
main.container { flex: 1; padding: 2rem 1rem; }
.section { margin-bottom: 2rem; }
.section-title { font-size: 1.25rem; font-weight: 600; color: var(--text); margin-bottom: 0.75rem; }

/* Link list */
.link-list { list-style: none; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.75rem; }
.link-item {
  display: flex; flex-direction: column; gap: 0.25rem;
  padding: 0.9rem 1rem; border: 1px solid var(--border); border-radius: 0.75rem;
  background-color: var(--card-bg); color: inherit; text-decoration: none;
  transition: transform 120ms ease, box-shadow 120ms ease, border-color 120ms ease;
}
.link-item:hover, .link-item:focus { transform: translateY(-2px); border-color: #cbd5e1; box-shadow: 0 6px 16px var(--shadow); outline: none; }
.link-title { font-weight: 600; }
.link-desc { color: var(--muted); font-size: 0.95rem; }

/* Footer */
.site-footer { border-top: 1px solid var(--border); background-color: var(--footer-bg); }
.footer-inner { padding: 1rem 0; text-align: center; color: var(--subtle); font-size: 0.95rem; }
.footer-inner a { color: var(--link); text-decoration: none; }
.footer-inner a:hover, .footer-inner a:focus { text-decoration: underline; outline: none; }

/* Responsive */
@media (max-width: 768px) {
  .header-inner { padding: 1.5rem 0 0.75rem; }
  .site-title { font-size: 1.5rem; }
  main.container { padding: 1.25rem 1rem; }
  .link-list { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .site-title { font-size: 1.35rem; }
  .site-tagline { font-size: 0.9rem; }
}