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

/* ===== Theme Variables ===== */
:root {
  --font-sans: "Inter", -apple-system, "PingFang SC", "Helvetica Neue", Arial, sans-serif;
  --radius: 16px;
  --radius-sm: 10px;
  --max-width: 1120px;
}

/* Light mode (default) */
:root, :root.light {
  --bg:           #ffffff;
  --bg-subtle:   #f8fafc;  /* slate-50 */
  --bg-card:     #ffffff;
  --bg-hover:    #f1f5f9;  /* slate-100 */
  --border:       rgba(0,0,0,0.06);   /* black/6 */
  --border-strong: rgba(0,0,0,0.10);
  --text:         #0f172a;  /* slate-950 */
  --text-muted:   #475569;  /* slate-600 */
  --text-dim:     #94a3b8;  /* slate-400 */
  --accent:       #0ea5e9;  /* sky-500 */
  --accent-bright:#38bdf8;  /* sky-400 */
  --accent-glow:  rgba(56,189,248,0.12);
  --pattern-fg:   rgba(15,23,42,0.04);
  --header-bg:    rgba(255,255,255,0.8);
  --btn-bg:       #0f172a;
  --btn-text:     #ffffff;
  --btn-hover:    #1e293b;
  --code-bg:      #f1f5f9;
}

/* Dark mode */
:root.dark {
  --bg:           #0f172a;  /* gray-950 */
  --bg-subtle:    #0f172a;
  --bg-card:      #0f172a;
  --bg-hover:     #1e293b;  /* slate-800 */
  --border:       rgba(255,255,255,0.10);
  --border-strong:rgba(255,255,255,0.15);
  --text:         #f8fafc;  /* slate-50 */
  --text-muted:   #94a3b8;  /* slate-400 */
  --text-dim:     #64748b;  /* slate-500 */
  --accent:       #38bdf8;  /* sky-400 */
  --accent-bright:#7dd3fc;  /* sky-300 */
  --accent-glow:  rgba(56,189,248,0.15);
  --pattern-fg:   rgba(255,255,255,0.04);
  --header-bg:    rgba(15,23,42,0.8);
  --btn-bg:       #334155;  /* slate-700 */
  --btn-text:     #ffffff;
  --btn-hover:    #475569;  /* slate-600 */
  --code-bg:      rgba(255,255,255,0.05);
}

/* System mode - follows OS */
@media (prefers-color-scheme: dark) {
  :root.system {
    --bg:           #0f172a;
    --bg-subtle:    #0f172a;
    --bg-card:      #0f172a;
    --bg-hover:     #1e293b;
    --border:       rgba(255,255,255,0.10);
    --border-strong:rgba(255,255,255,0.15);
    --text:         #f8fafc;
    --text-muted:   #94a3b8;
    --text-dim:     #64748b;
    --accent:       #38bdf8;
    --accent-bright:#7dd3fc;
    --accent-glow:  rgba(56,189,248,0.15);
    --pattern-fg:   rgba(255,255,255,0.04);
    --header-bg:    rgba(15,23,42,0.8);
    --btn-bg:       #334155;
    --btn-text:     #ffffff;
    --btn-hover:    #475569;
    --code-bg:      rgba(255,255,255,0.05);
  }
}

@media (prefers-color-scheme: light) {
  :root.system {
    --bg:           #ffffff;
    --bg-subtle:   #f8fafc;
    --bg-card:     #ffffff;
    --bg-hover:    #f1f5f9;
    --border:       rgba(0,0,0,0.06);
    --border-strong: rgba(0,0,0,0.10);
    --text:         #0f172a;
    --text-muted:   #475569;
    --text-dim:     #94a3b8;
    --accent:       #0ea5e9;
    --accent-bright:#38bdf8;
    --accent-glow:  rgba(56,189,248,0.12);
    --pattern-fg:   rgba(15,23,42,0.04);
    --header-bg:    rgba(255,255,255,0.8);
    --btn-bg:       #0f172a;
    --btn-text:     #ffffff;
    --btn-hover:    #1e293b;
    --code-bg:      #f1f5f9;
  }
}

body {
  font-family: var(--font-sans);
  line-height: 1.7;
  color: var(--text);
  background: var(--bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background 0.3s, color 0.3s;
}

a { color: inherit; text-decoration: none; }

/* ===== Pattern Background ===== */
.pattern-bg {
  background-image: repeating-linear-gradient(
    315deg,
    var(--pattern-fg) 0,
    var(--pattern-fg) 1px,
    transparent 0,
    transparent 50%
  );
  background-size: 10px 10px;
}

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--border);
  background: var(--header-bg);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
}
.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.header-left {
  display: flex;
  align-items: center;
  gap: 16px;
}
.site-logo {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.5px;
  display: flex;
  align-items: center;
}
.site-logo span { color: var(--accent-bright); }

.site-nav {
  display: flex;
  gap: 28px;
}
.site-nav a {
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 500;
  transition: color 0.15s;
}
.site-nav a:hover { color: var(--text); }
.site-nav a.active { color: var(--accent-bright); }

.header-right {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* Theme toggle — matches Tailwind CSS official site */
.theme-toggle {
  display: inline-grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2px;
  border-radius: 9999px;
  padding: 3px;
}
:root.light .theme-toggle,
:root.system .theme-toggle {
  background: rgba(15, 23, 42, 0.05);  /* gray-950/5 */
  color: #0f172a;
}
:root.dark .theme-toggle {
  background: rgba(255, 255, 255, 0.10);  /* white/10 */
  color: #ffffff;
}
.theme-toggle button {
  border: none;
  background: transparent;
  cursor: pointer;
  border-radius: 9999px;
  padding: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: inherit;
  transition: background 0.15s;
}
@media (min-width: 640px) {
  .theme-toggle button { padding: 0; }
}
.theme-toggle button svg {
  width: 28px;
  height: 28px;
  display: block;
}
/* Checked state */
:root.light .theme-toggle button.active,
:root.system .theme-toggle button.active {
  background: #ffffff;
  box-shadow: 0 0 0 1px rgba(15, 23, 42, 0.10);
}
:root.dark .theme-toggle button.active {
  background: #334155;  /* gray-700 */
  color: #ffffff;
  box-shadow: none;
}

/* Mobile menu */
.menu-toggle {
  display: none;
  font-size: 1.3rem;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text);
  line-height: 1;
}

/* ===== Main ===== */
.site-main {
  flex: 1;
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 48px 24px;
}

/* ===== Hero ===== */
.hero {
  text-align: center;
  padding: 64px 20px 48px;
}
.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  letter-spacing: -1.5px;
  margin-bottom: 16px;
  line-height: 1.1;
}
.hero p {
  font-size: 1.2rem;
  color: var(--text-muted);
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.6;
}

/* ===== Cards ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin-top: 32px;
}
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 8px;
  transition: border-color 0.2s, transform 0.15s;
  outline: 1px solid transparent;
}
.card:hover {
  border-color: var(--border-strong);
  transform: translateY(-2px);
}
.card-inner {
  padding: 20px;
}
.card-icon {
  font-size: 1.8rem;
  margin-bottom: 12px;
  display: block;
}
.card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--text);
}
.card p {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.6;
}
.card .card-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-top: 14px;
  color: var(--accent-bright);
  font-size: 0.85rem;
  font-weight: 500;
}

/* ===== Section ===== */
.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  margin-bottom: 8px;
}
.section-desc {
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: 32px;
}

/* ===== Code Block ===== */
.code-block {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  font-family: "JetBrains Mono", "SF Mono", monospace;
  font-size: 0.85rem;
  line-height: 1.7;
  overflow-x: auto;
  color: var(--text);
}
.code-block .token-keyword { color: #c084fc; }
.code-block .token-string { color: #86efac; }
.code-block .token-comment { color: var(--text-dim); }

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg);
}
.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 40px 24px;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 32px;
}
.footer-brand {
  flex-shrink: 0;
}
.footer-logo {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
}
.footer-logo span { color: var(--accent-bright); }
.footer-desc {
  color: var(--text-dim);
  font-size: 0.85rem;
  max-width: 240px;
}
.footer-cols {
  display: flex;
  gap: 48px;
  flex-wrap: wrap;
}
.footer-col h4 {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 12px;
}
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 8px; }
.footer-col a {
  color: var(--text-muted);
  font-size: 0.85rem;
  transition: color 0.15s;
}
.footer-col a:hover { color: var(--accent-bright); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 16px 24px;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.8rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .menu-toggle { display: block; }
  .site-nav {
    display: none;
    position: absolute;
    top: 56px;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 12px 24px;
    gap: 12px;
  }
  .site-nav.open { display: flex; }
  .hero h1 { font-size: 2.2rem; }
  .hero { padding: 40px 20px 32px; }
  .footer-inner { flex-direction: column; }
  .footer-cols { gap: 32px; }
}