html, body {
        margin: 0;
        padding: 0;
        width: 100%;
        height: 100vh;
        background: #000;
        color: #ccc;
        font-family: "Fira Code", monospace;
      }
      body {
        display: flex;
        flex-direction: column;
      }
      header {
        background: #111;
        color: #888;
        padding: 8px 16px;
        font-size: 12px;
        border-bottom: 1px solid #222;
      }
      header a { color: #ccc; text-decoration: none; }
      header a:hover { text-decoration: underline; }
      main {
        flex: 1;
        display: flex;
        justify-content: center;
        align-items: center;
        overflow: hidden;
      }
      pre { font-family: "Fira Code", monospace; font-size: 14px; margin: 0; }
      canvas { display: block; }