:root{
  --bg:#FBFBFA;
  --surface:#FFFFFF;
  --ink:#16161A;
  --muted:#6B6B73;
  --line:#ECECEA;
  --accent:#4F46E5;
  --accent-press:#3B33C4;
  --ok:#15803D;
  --err:#C2410C;
  --radius:16px;
  --shadow:0 1px 2px rgba(16,16,26,.04), 0 8px 28px rgba(16,16,26,.06);
  --maxw:720px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0;background:var(--bg);color:var(--ink)}
body{font-size:16px;line-height:1.6;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
code{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:.92em;background:#F2F2F0;padding:.1em .4em;border-radius:6px}
.wrap{max-width:var(--maxw);margin:0 auto;padding:28px 22px 64px}

.head{display:flex;align-items:center;margin-bottom:40px}
.mark{font-weight:600;letter-spacing:-.01em;font-size:15px;color:var(--muted)}
.mark .dot{color:var(--accent)}

h1{font-size:clamp(28px,6vw,40px);line-height:1.1;letter-spacing:-.02em;margin:0 0 10px;font-weight:680}
.lede{margin:0 0 26px;color:var(--muted);font-size:17px;max-width:52ch}

/* ---- tool ---- */
.tool{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.drop{border:1.5px dashed #D8D8D4;border-radius:14px;padding:38px 18px;text-align:center;cursor:pointer;transition:border-color .18s ease,background .18s ease,transform .18s ease;outline:none}
.drop:hover{border-color:#BDBDBC}
.drop:focus-visible{border-color:var(--accent);box-shadow:0 0 0 4px rgba(79,70,229,.14)}
.drop.drag{border-color:var(--accent);background:#F5F4FF;transform:translateY(-1px)}
.drop-ico{width:30px;height:30px;color:var(--accent);margin-bottom:12px}
.drop-title{margin:0;font-weight:560;font-size:16px}
.drop-hint{margin:8px 0 0;color:var(--muted);font-size:13px;letter-spacing:.02em}

.chip{display:flex;align-items:center;gap:10px;margin-top:14px;padding:10px 12px;border:1px solid var(--line);border-radius:10px;background:#FAFAF9}
.chip-ico{color:var(--accent);font-size:15px}
.chip-name{font-weight:560;font-size:14px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.chip-meta{color:var(--muted);font-size:13px;margin-left:auto;font-variant-numeric:tabular-nums}
.chip-x{border:none;background:none;color:var(--muted);font-size:20px;line-height:1;cursor:pointer;padding:0 4px}
.chip-x:hover{color:var(--ink)}

.cta{display:block;width:100%;margin-top:16px;padding:14px 18px;border:none;border-radius:12px;background:var(--accent);color:#fff;font-size:16px;font-weight:600;cursor:pointer;transition:background .16s ease,transform .08s ease}
.cta:hover{background:var(--accent-press)}
.cta:active{transform:translateY(1px)}
.cta:disabled{background:#D8D8D4;color:#fff;cursor:not-allowed}

.err{margin:14px 0 0;color:var(--err);font-size:14px}

.busy{display:flex;align-items:center;gap:10px;margin-top:16px;color:#2c2c31;font-size:15px;font-weight:500}
.spinner{width:16px;height:16px;border:2px solid var(--line);border-top-color:var(--accent);border-radius:50%;animation:spin .7s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}

/* ---- result ---- */
.result{margin-top:18px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.res-top{display:flex;gap:36px;margin-bottom:16px}
.res-stat{display:flex;flex-direction:column}
.res-num{font-size:30px;font-weight:680;letter-spacing:-.02em;font-variant-numeric:tabular-nums;line-height:1}
.res-lab{color:var(--muted);font-size:13px;margin-top:4px}
.wave{width:100%;height:64px;display:block;margin:4px 0 18px;border-radius:10px;background:#FAFAF9}
.res-actions{display:flex;gap:12px}
.btn-down,.btn-copy{flex:1;text-align:center;padding:13px 16px;border-radius:11px;font-size:15px;font-weight:600;text-decoration:none;cursor:pointer;transition:background .16s ease,border-color .16s ease,transform .08s ease}
.btn-down{background:var(--accent);color:#fff}
.btn-down:hover{background:var(--accent-press)}
.btn-copy{background:var(--surface);color:var(--ink);border:1.5px solid var(--line)}
.btn-copy:hover{border-color:#BDBDBC}
.btn-copy:active,.btn-down:active{transform:translateY(1px)}
.btn-copy.done{color:var(--ok);border-color:var(--ok)}

.notes{margin-top:18px;border-top:1px solid var(--line);padding-top:14px}
.notes summary{cursor:pointer;color:var(--muted);font-size:14px}
.note-list{margin:12px 0 0;padding-left:22px;color:var(--ink);font-size:14px;max-height:200px;overflow:auto;font-variant-numeric:tabular-nums}
.note-list li{margin:2px 0}

/* ---- doc ---- */
.doc{margin-top:46px}
.doc h2{font-size:19px;letter-spacing:-.01em;margin:30px 0 10px;font-weight:640}
.doc p{color:#2c2c31;margin:0 0 4px}
.steps{padding-left:20px;color:#2c2c31;margin:0}
.steps li{margin:6px 0}
.faq{margin:0}
.faq dt{font-weight:600;margin-top:14px}
.faq dd{margin:4px 0 0;color:var(--muted)}

.foot{display:flex;justify-content:space-between;margin-top:48px;padding-top:18px;border-top:1px solid var(--line);color:var(--muted);font-size:13px}

/* ---- toast ---- */
.toast{position:fixed;left:50%;bottom:28px;transform:translateX(-50%) translateY(8px);background:var(--ink);color:#fff;padding:11px 18px;border-radius:10px;font-size:14px;opacity:0;pointer-events:none;transition:opacity .2s ease,transform .2s ease;box-shadow:0 8px 30px rgba(0,0,0,.2)}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0)}

/* ---- responsive ---- */
@media (max-width:520px){
  .wrap{padding:20px 16px 48px}
  .tool,.result{padding:18px}
  .res-top{gap:24px}
  .res-num{font-size:26px}
  .res-actions{flex-direction:column}
  .drop{padding:30px 14px}
}

@media (prefers-reduced-motion:reduce){
  *{transition:none!important;animation:none!important}
}