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

/* === Variables === */
:root {
  --bg: #0a0a0a;
  --bg-surface: #111;
  --bg-elevated: #1a1a1a;
  --border: #222;
  --border-hover: #333;
  --text: #ccc;
  --text-muted: #666;
  --text-dim: #555;
  --accent: #4ade80;
  --error: #f87171;
  --font-mono: ui-monospace, 'SF Mono', 'Cascadia Code', Consolas, monospace;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --max-width: 1100px;
}

/* === Base === */
html {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.6;
}

a {
  color: var(--text-muted);
  text-decoration: none;
}
a:hover {
  color: var(--text);
}

/* === Header === */
.header {
  max-width: var(--max-width);
  margin: 0 auto;
  border-bottom: 1px solid var(--border);
}

/* === Nav === */
.nav {
  display: flex;
  align-items: center;
  gap: 24px;
  padding: 16px 24px;
}
.nav-logo {
  color: var(--text-muted);
  font-size: 12px;
  letter-spacing: 2px;
  text-transform: uppercase;
}
.nav-links {
  display: flex;
  gap: 16px;
  font-size: 12px;
}

/* === UserAgent Bar === */
.ua-bar {
  padding: 6px 24px;
  font-size: 11px;
  color: var(--text-dim);
  border-top: 1px solid var(--border);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  cursor: pointer;
  transition: color 0.15s;
}
.ua-bar:hover {
  color: var(--text-muted);
}

/* === Main === */
.main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 24px;
}

/* === Footer === */
.footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 24px;
  border-top: 1px solid var(--border);
  color: var(--text-dim);
  font-size: 12px;
  text-align: center;
}

/* === Home: Tool Cards === */
.category-group {
  margin-bottom: 32px;
}
.category-title {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-muted);
  margin-bottom: 12px;
}
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
}
.tool-card {
  display: block;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 20px;
  transition: border-color 0.15s;
}
.tool-card:hover {
  border-color: var(--border-hover);
}
.tool-card-name {
  color: var(--text);
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 4px;
}
.tool-card-desc {
  color: var(--text-dim);
  font-size: 12px;
}