:root{--ink:#1f2937;--muted:#6b7280;--line:#e5e7eb;--bg:#ffffff;
--card:#f9fafb;--accent:#0d9488;--accent-dark:#0f766e;--radius:12px}
*{box-sizing:border-box}
body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,
Helvetica,Arial,sans-serif;color:var(--ink);background:var(--bg);line-height:1.6}
.wrap{max-width:720px;margin:0 auto;padding:0 20px}
.site-header{border-bottom:1px solid var(--line);background:#fff}
.site-header .wrap{display:flex;align-items:center;justify-content:space-between;
padding-top:14px;padding-bottom:14px}
.brand{font-weight:700;font-size:1.1rem;color:var(--ink);text-decoration:none}
.topnav a{margin-left:18px;color:var(--muted);text-decoration:none;font-size:.95rem}
.topnav a:hover{color:var(--accent-dark)}
main{padding:40px 0 56px}
h1{font-size:1.9rem;line-height:1.25;margin:0 0 8px}
.lede{color:var(--muted);margin:0 0 24px}
.tool-card{background:var(--card);border:1px solid var(--line);border-radius:
var(--radius);padding:28px;margin-bottom:28px}
.field{margin-bottom:16px}
label{display:block;font-size:.85rem;font-weight:600;margin-bottom:6px}
input[type=number]{width:100%;padding:12px;border:1px solid var(--line);
border-radius:8px;font-size:1rem}
input[type=range]{width:100%}
.btn{background:var(--accent);color:#fff;border:0;border-radius:8px;
padding:12px 20px;font-size:1rem;font-weight:600;cursor:pointer;width:100%}
.btn:hover{background:var(--accent-dark)}
.result{margin-top:20px;background:#fff;border:1px solid var(--line);
border-radius:8px;padding:18px;display:none}
.result.show{display:block}
.result .big{font-size:2rem;font-weight:700;color:var(--accent-dark)}
.result .row{display:flex;justify-content:space-between;align-items:center;
padding:6px 0;border-bottom:1px dashed var(--line)}
.how h2{font-size:1.3rem;margin:32px 0 10px}
.how ol{padding-left:20px;color:var(--muted)}
.site-footer{border-top:1px solid var(--line);padding:24px 0;color:var(--muted);
font-size:.85rem}
.site-footer .wrap{display:flex;flex-wrap:wrap;gap:8px 24px;justify-content:space-between}
.site-footer a{color:var(--muted);text-decoration:none}
.site-footer a:hover{color:var(--accent-dark)}
.prose h1{font-size:1.7rem}
.prose p{color:var(--ink)}
.tabs{display:flex;gap:8px;margin-bottom:20px;flex-wrap:wrap}
.tab{flex:1;min-width:140px;background:#fff;border:1px solid var(--line);
border-radius:8px;padding:10px 8px;font-size:.9rem;font-weight:600;
color:var(--muted);cursor:pointer}
.tab[aria-selected="true"]{background:var(--accent);border-color:var(--accent);
color:#fff}
.mode.hidden{display:none}
.time-row{display:flex;gap:8px}
.time-row input[type=time]{flex:1;padding:12px;border:1px solid var(--line);
border-radius:8px;font-size:1rem}
.btn.ghost{width:auto;background:#fff;color:var(--accent-dark);
border:1px solid var(--accent)}
.btn.ghost:hover{background:#f0fdfa}
.nap-btns{display:grid;gap:10px;margin-bottom:20px}
.cycle-chip{display:inline-block;background:#eef6f5;border-radius:999px;
padding:4px 12px;font-size:.85rem;font-weight:600;color:var(--accent-dark)}
.cycle-chip em{font-style:normal;font-weight:700;text-decoration:underline}
.result-title{margin:0 0 12px;font-size:1.05rem}
.hint{color:var(--muted);font-size:.88rem;margin:12px 0 0}
.faq h2{font-size:1.3rem;margin:32px 0 10px}
.faq h3{font-size:1.05rem;margin:20px 0 6px}
.faq p{color:var(--muted);margin:0 0 12px}
.rating{display:inline-block;padding:4px 14px;border-radius:999px;
font-weight:700;font-size:.9rem}
.rating.low{background:#fee2e2;color:#991b1b}
.rating.average{background:#e0f2fe;color:#075985}
.rating.good{background:#fef9c3;color:#854d0e}
.rating.excellent{background:#dcfce7;color:#166534}
table.bench{width:100%;border-collapse:collapse;margin:16px 0;font-size:.92rem}
table.bench th,table.bench td{border:1px solid var(--line);padding:8px 10px;
text-align:left}
table.bench th{background:var(--card);font-weight:700}
table.bench td{color:var(--muted)}
.formula{background:#fff;border:1px solid var(--line);border-radius:8px;
padding:14px 18px;margin:16px 0;font-size:1.05rem;font-weight:600;
color:var(--accent-dark)}
@media(max-width:520px){h1{font-size:1.55rem}.tool-card{padding:20px}}