:root {
  --bg: #0f1117; --surface: #181c27;
  --accent: #00c9a7; --text: #e2e8f0;
  --muted: #64748b; --mono: 'IBM Plex Mono', monospace;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body { background: var(--bg); color: var(--text);
       font-family: sans-serif; padding: 2rem; }
header { border-bottom: 1px solid #252a38;
         padding-bottom: 1rem; margin-bottom: 2rem; }
.brand { font-size: 1.1rem; font-weight: 600; color: var(--accent); }