:root{
  --paper:#faf7f0; --card:#fffdf8; --ink:#2b2620; --muted:#8a7f6d;
  --red:#b03a2e; --red-soft:#f6e3df; --line:#e6ddcd; --gold:#c8963e;
  --done:#3e7d4e;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{background:var(--paper);color:var(--ink);font-family:"PingFang SC","Microsoft YaHei","Noto Sans SC",system-ui,sans-serif;min-height:100vh;display:flex;flex-direction:column}
a{color:var(--red)}
button{font-family:inherit;cursor:pointer}

.topbar{display:flex;justify-content:space-between;align-items:center;gap:16px;padding:18px 28px;border-bottom:1px solid var(--line);flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:14px}
.seal{display:inline-flex;align-items:center;justify-content:center;width:48px;height:48px;background:var(--red);color:#fff;font-family:"Noto Serif SC","Songti SC",serif;font-size:26px;font-weight:700;border-radius:8px;box-shadow:0 2px 8px rgba(176,58,46,.3)}
.brand h1{margin:0;font-family:"Noto Serif SC","Songti SC",serif;font-size:26px;letter-spacing:2px}
.brand p{margin:2px 0 0;color:var(--muted);font-size:13px}
.top-actions{display:flex;align-items:center;gap:12px}
select{padding:6px 8px;border:1px solid var(--line);border-radius:8px;background:#fff;color:var(--ink);font-size:14px}
.ghost-btn{background:transparent;border:1px solid var(--line);border-radius:8px;padding:7px 14px;font-size:14px;color:var(--ink)}
.ghost-btn:hover{border-color:var(--red);color:var(--red)}

main{flex:1;width:100%;max-width:880px;margin:0 auto;padding:28px 20px 40px}
.intro{color:var(--muted);font-size:15px;line-height:1.7;margin:0 0 22px}

.mode-tabs{display:flex;gap:10px;margin:0 0 18px;flex-wrap:wrap}
.mode-tab{border:1px solid var(--line);background:var(--card);border-radius:24px;padding:9px 22px;font-size:15px;font-family:"Noto Serif SC","Songti SC",serif;letter-spacing:1px;color:var(--muted)}
.mode-tab.active{background:var(--red);border-color:var(--red);color:#fff}

.card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:24px 26px;margin-bottom:20px}
.conv-row{display:flex;gap:12px;flex-wrap:wrap}
.conv-input{flex:1;min-width:200px;font-size:22px;padding:12px 14px;border:1px solid var(--line);border-radius:10px;background:#fff;color:var(--ink);font-variant-numeric:tabular-nums}
.conv-input:focus{outline:none;border-color:var(--gold)}
.unit-select{font-size:16px;padding:12px 10px;border-radius:10px}
.hint{color:var(--muted);font-size:13px;line-height:1.6;margin:12px 0 0}
.input-error{color:var(--red);font-size:14px;margin:12px 0 0}
.prec-row{margin-top:16px;font-size:14px;color:var(--muted);display:flex;align-items:center;gap:8px}
.prec-row select{margin-left:6px}

.results{list-style:none;margin:16px 0 0;padding:0}
.result-row{display:flex;align-items:baseline;gap:10px;padding:10px 2px;border-bottom:1px dashed var(--line)}
.result-row:last-child{border-bottom:0}
.r-label{color:var(--muted);font-size:14px;min-width:158px}
.r-value{font-size:21px;font-weight:600;font-variant-numeric:tabular-nums;white-space:nowrap}
.r-unit{color:var(--muted);font-size:14px}
.copy-btn{margin-left:auto;background:transparent;border:1px solid var(--line);border-radius:6px;padding:4px 12px;font-size:12px;color:var(--muted);flex-shrink:0}
.copy-btn:hover{border-color:var(--red);color:var(--red)}
.frac-err{color:var(--muted);font-size:13px;margin:12px 0 0}
.frac-err strong{color:var(--ink)}

.table-head{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-bottom:8px}
.table-head h3{margin:0;font-family:"Noto Serif SC","Songti SC",serif;font-size:19px;letter-spacing:1px}
.frac-table{width:100%;border-collapse:collapse;font-variant-numeric:tabular-nums}
.frac-table th,.frac-table td{padding:7px 10px;border-bottom:1px solid var(--line);text-align:right;font-size:15px}
.frac-table th:first-child,.frac-table td:first-child{text-align:left}
.frac-table thead th{color:var(--muted);font-weight:600;border-bottom:2px solid var(--line);font-size:13px}
.frac-table tbody tr:last-child td{border-bottom:0;font-weight:600}

footer{border-top:1px solid var(--line);padding:20px 28px;text-align:center;color:var(--muted);font-size:13px}
.foot-links{display:flex;flex-wrap:wrap;gap:8px 20px;justify-content:center;align-items:center;margin-bottom:12px}
.foot-label{font-weight:600;color:var(--ink)}
.foot-links a{color:var(--muted);text-decoration:none}
.foot-links a:hover{color:var(--red);text-decoration:underline}

@media (max-width:560px){
  main{padding:20px 14px 32px}
  .card{padding:18px 16px}
  .conv-input{font-size:19px;min-width:0}
  .r-label{min-width:104px;font-size:13px}
  .r-value{font-size:18px}
}

@media print{
  .topbar,footer,.mode-tabs,.conv-card,.no-print,.copy-btn{display:none!important}
  body{background:#fff}
  main{padding:0;max-width:none}
  .card{border:0;padding:0}
  .frac-table th,.frac-table td{border-bottom:1px solid #ccc;color:#000}
}