:root {
  --bg: #0f1115; --surface: #1a1d24; --border: #2a2f3a;
  --text: #e8eaed; --muted: #9aa0a6; --accent: #5b8def;
  --radius: 12px; --font: system-ui, -apple-system, sans-serif;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: var(--font); background: var(--bg); color: var(--text); min-height: 100vh; padding: 24px 16px; }
.container { max-width: 520px; margin: 0 auto; }
header { text-align: center; margin-bottom: 28px; }
h1 { font-size: 1.6rem; font-weight: 700; margin-bottom: 8px; }
.subtitle { color: var(--muted); font-size: 0.95rem; }
.category-select { margin-bottom: 24px; }
label { display: block; font-size: 0.85rem; color: var(--muted); margin-bottom: 6px; }
select, input[type="number"] {
  background: var(--surface); border: 1px solid var(--border); color: var(--text);
  padding: 12px 14px; border-radius: 8px; font-size: 1rem; outline: none; width: 100%;
}
select:focus, input:focus { border-color: var(--accent); }
.converter { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; }
.form-group { margin-bottom: 16px; }
.input-row { display: flex; gap: 10px; }
.input-row input { flex: 1; }
.input-row select { width: 130px; flex-shrink: 0; }
.swap-btn {
  text-align: center; font-size: 1.4rem; cursor: pointer; color: var(--accent);
  margin: 4px 0 12px; user-select: none;
}
.swap-btn:hover { opacity: 0.8; }
.result { margin-top: 20px; padding: 14px; background: var(--surface); border-radius: 8px; border: 1px solid var(--border); text-align: center; font-size: 1.1rem; min-height: 48px; display: none; }
.result.show { display: block; }
footer { text-align: center; margin-top: 36px; color: var(--muted); font-size: 0.8rem; }