:root {
    --fg: #1a1a2e;
    --bg: #fafafa;
    --card: #ffffff;
    --accent: #4f46e5;
    --border: #e2e2ea;
    --muted: #6b7280;
}
* { box-sizing: border-box; }
body { margin: 0; font-family: -apple-system, Segoe UI, Roboto, sans-serif; color: var(--fg); background: var(--bg); line-height: 1.5; }
.container { max-width: 720px; margin: 0 auto; padding: 24px 16px 64px; }

.site-header { display: flex; justify-content: space-between; align-items: center; padding: 16px 24px; border-bottom: 1px solid var(--border); background: var(--card); }
.brand { font-weight: 700; text-decoration: none; color: var(--fg); font-size: 1.1rem; }
.top-nav a { margin-left: 16px; text-decoration: none; color: var(--muted); font-size: 0.9rem; }
.top-nav a:hover { color: var(--accent); }

h1 { font-size: 1.6rem; margin-bottom: 8px; }
.intro { color: var(--muted); margin-bottom: 20px; }

.disclaimer { background: #fff7ed; border: 1px solid #fdba74; color: #9a3412; padding: 10px 14px; border-radius: 8px; font-size: 0.9rem; margin-bottom: 16px; }

.tool-card { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 20px; }
.mode-toggle { display: flex; gap: 8px; margin-bottom: 12px; }
.mode-btn { border: 1px solid var(--border); background: #fff; padding: 6px 14px; border-radius: 999px; cursor: pointer; font-size: 0.85rem; }
.mode-btn.active { background: var(--accent); color: #fff; border-color: var(--accent); }

textarea, input[type=text] { width: 100%; font-family: ui-monospace, monospace; font-size: 0.9rem; padding: 10px; border: 1px solid var(--border); border-radius: 8px; }
.file-name { font-size: 0.85rem; color: var(--muted); margin-top: 6px; }

.algo-row { display: flex; align-items: center; gap: 8px; margin: 14px 0 6px; }
.algo-row label { font-size: 0.8rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.03em; }
.algo-badge { background: #eef2ff; color: var(--accent); font-weight: 600; padding: 2px 10px; border-radius: 6px; font-size: 0.85rem; }

.output-row label { font-size: 0.8rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.03em; }
.output-wrap { display: flex; gap: 8px; margin-top: 4px; }
.output-wrap input { flex: 1; background: #f9fafb; }
.copy-btn { border: 1px solid var(--border); background: #fff; border-radius: 8px; padding: 0 16px; cursor: pointer; }
.copy-btn:hover { border-color: var(--accent); color: var(--accent); }
.status { min-height: 20px; font-size: 0.85rem; color: var(--accent); margin-top: 8px; }

.faq-section { margin-top: 32px; }
.faq-item { border-bottom: 1px solid var(--border); padding: 12px 0; }
.faq-item summary { cursor: pointer; font-weight: 600; }
.faq-item p { color: var(--muted); margin: 8px 0 0; }

.related-tools { margin-top: 32px; }
.related-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 10px; }
.related-grid a { display: block; padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px; text-decoration: none; color: var(--fg); font-size: 0.85rem; background: var(--card); }
.related-grid a:hover { border-color: var(--accent); color: var(--accent); }

.site-footer { text-align: center; color: var(--muted); font-size: 0.8rem; padding: 24px; border-top: 1px solid var(--border); }