:root{color:#e2e8f0;background:#08111f;font:16px system-ui}body{margin:0}main{max-width:900px;margin:auto;padding:24px}.viewport{background:#0f172a;border:1px solid #334155;height:480px}.controls{gap:8px;margin:16px 0;display:flex}button{padding:8px 12px}output{margin-top:12px;font-family:monospace;display:block}