:root{--ink:#1b1f1c;--muted:#5b625e;--line:#d9ddda;--surface:#f6f7f6;--bg:#fff}@media (prefers-color-scheme:dark){:root{--ink:#eef1ef;--muted:#a6ada9;--line:#333a36;--surface:#1b1f1c;--bg:#121513}}*{box-sizing:border-box;border-radius:0}body{color:var(--ink);background:var(--bg);margin:0;font-family:Arial,Helvetica,sans-serif}main{max-width:720px;margin:0 auto;padding:28px 20px}h1{margin:0 0 8px;font-size:28px}p,li{line-height:1.5}.muted{color:var(--muted)}.box{border:1px solid var(--line);background:var(--surface);margin:16px 0;padding:16px}.btn{background:var(--ink);color:var(--bg);font:inherit;cursor:pointer;border:0;padding:10px 16px;text-decoration:none;display:inline-block}.btn:focus-visible,a:focus-visible{outline:2px solid var(--ink);outline-offset:2px}.btn-secondary{color:var(--ink);border:1px solid var(--ink);background:0 0}.err{border-left:3px solid #c62828;padding-left:12px}