```css
:root { font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif; }
body { margin: 0; background: #f6f7f9; color: #111; }
.topbar { background: #fff; border-bottom: 1px solid #eee; }
.topbar .wrap { max-width: 960px; margin: 0 auto; padding: 10px 16px; display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.container { max-width: 960px; margin: 32px auto; padding: 0 16px; }
.card { background: #fff; border-radius: 16px; padding: 20px; box-shadow: 0 6px 24px rgba(0,0,0,.06); margin-bottom: 16px; }
.row { display: flex; align-items: center; gap: 12px; justify-content: space-between; }
.wrap { flex-wrap: wrap; gap: 8px; }
.grid { display: grid; gap: 8px; max-width: 360px; }
input, button { font: inherit; padding: 10px 12px; border-radius: 10px; border: 1px solid #ddd; }
button { cursor: pointer; border: 1px solid #ccc; background: #f4f4f4; }
button:hover { background: #eee; }
.error { color: #b00020; margin: 8px 0; }
.result { background: #0f172a; color: #e5e7eb; padding: 12px; border-radius: 12px; overflow: auto; max-height: 320px; }
```