:root{--bg: #f5f6f8;--card-bg: #ffffff;--text: #1a1d21;--muted: #6b7280;--border: #d1d5db;--accent: #2563eb;--error: #b91c1c;color-scheme:light dark}@media(prefers-color-scheme:dark){:root{--bg: #111418;--card-bg: #1c2128;--text: #e6e8eb;--muted: #9aa1a9;--border: #3a414b;--accent: #60a5fa;--error: #f87171}}*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,Segoe UI,sans-serif;background:var(--bg);color:var(--text);display:flex;justify-content:center;align-items:flex-start;min-height:100vh;padding:2rem 1rem}.card{background:var(--card-bg);border:1px solid var(--border);border-radius:12px;padding:2rem;width:100%;max-width:26rem;display:flex;flex-direction:column;gap:1rem}h1{font-size:1.4rem;margin:0 0 .5rem;text-align:center}.row{display:flex;flex-direction:column;gap:.35rem}label{font-size:.85rem;color:var(--muted)}input,select{font:inherit;color:inherit;background:var(--bg);border:1px solid var(--border);border-radius:8px;padding:.55rem .75rem}input:focus,select:focus{outline:2px solid var(--accent);outline-offset:-1px}.swap-row{align-items:center}button{font:inherit;color:inherit;background:transparent;border:1px solid var(--border);border-radius:8px;padding:.4rem 1rem;cursor:pointer}button:hover{border-color:var(--accent);color:var(--accent)}.result{margin-top:.5rem;padding:.9rem;border-radius:8px;background:var(--bg);text-align:center;font-size:1.05rem;min-height:3rem;display:flex;align-items:center;justify-content:center}.result strong{color:var(--accent)}.error{color:var(--error);font-size:.95rem}.hint{color:var(--muted);font-size:.95rem}