:root {
  --bg-color: #121212;
  --text-color: #e0e0e0;
  --card-bg: #1e1e1e;
  --card-border: #2a2a2a;
  --card-shadow: rgba(0,0,0,0.5);
  --logo-color: #64a8f0;
  --tagline-color: #7d7d7d;
  --heading-color: #b0b0b0;
  --link-bg: #252525;
  --link-border: #333;
  --link-text: #90bdf7;
  --link-hover-bg: #2a2a3a;
  --link-hover-border: #64a8f0;
  --link-hover-text: #64a8f0;
  --muted: #9a9a9a;
  --code-bg: #0f0f0f;
  --code-border: #2a2a2a;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg-color: #f5f5f5;
    --text-color: #333333;
    --card-bg: #ffffff;
    --card-border: #e0e0e0;
    --card-shadow: rgba(0,0,0,0.1);
    --logo-color: #2c3e50;
    --tagline-color: #666;
    --heading-color: #555;
    --link-bg: #f0f0f0;
    --link-border: #ddd;
    --link-text: #2c3e50;
    --link-hover-bg: #e8f4f8;
    --link-hover-border: #3498db;
    --link-hover-text: #3498db;
    --muted: #5f5f5f;
    --code-bg: #fafafa;
    --code-border: #e6e6e6;
  }
}

* { box-sizing: border-box; }
html, body { height: 100%; }

body {
  font-family: Arial, sans-serif;
  background: var(--bg-color);
  color: var(--text-color);
  margin: 0;
  padding: 32px 20px;
  transition: background-color 0.3s ease, color 0.3s ease;
}

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

.header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.brand .logo {
  font-size: 28px;
  font-weight: bold;
  color: var(--logo-color);
  letter-spacing: 1px;
}

.brand .tagline {
  font-size: 14px;
  color: var(--tagline-color);
}

.nav a {
  color: var(--link-text);
  text-decoration: none;
  border: 1px solid var(--link-border);
  background: var(--link-bg);
  padding: 10px 12px;
  border-radius: 8px;
  display: inline-block;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.nav a:hover {
  background: var(--link-hover-bg);
  border-color: var(--link-hover-border);
  color: var(--link-hover-text);
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  box-shadow: 0 4px 32px var(--card-shadow);
  padding: 28px;
  transition: background-color 0.3s ease, border-color 0.3s ease;
}

h1 {
  margin: 0 0 10px 0;
  font-size: 22px;
  color: var(--heading-color);
  font-weight: bold;
}

h2 {
  margin: 28px 0 10px 0;
  font-size: 18px;
  color: var(--heading-color);
}

h3 {
  margin: 18px 0 6px 0;
  font-size: 15px;
  color: var(--heading-color);
}

p { line-height: 1.55; }
.small { color: var(--muted); font-size: 13px; }

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 12px;
  margin-top: 16px;
}

.tile {
  display: block;
  text-decoration: none;
  color: inherit;
  background: var(--link-bg);
  border: 1px solid var(--link-border);
  border-radius: 10px;
  padding: 14px 16px;
  transition: background 0.15s, border-color 0.15s;
}

.tile:hover {
  background: var(--link-hover-bg);
  border-color: var(--link-hover-border);
}

.tile .title {
  font-weight: bold;
  color: var(--link-text);
  margin-bottom: 6px;
}

.tile .desc {
  font-size: 13px;
  color: var(--muted);
}

ul { margin: 8px 0 0 18px; }
li { margin: 6px 0; }

code, pre {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}

pre {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: 10px;
  padding: 14px;
  overflow: auto;
}

details {
  margin-top: 12px;
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: 10px;
  padding: 12px 14px;
}

summary {
  cursor: pointer;
  font-weight: bold;
  color: var(--link-text);
}

.footer {
  margin-top: 22px;
  color: var(--muted);
  font-size: 12px;
}

hr {
  border: none;
  border-top: 1px solid var(--card-border);
  margin: 18px 0;
}