:root {
      --bg: #fbfbfa;
      --panel: #ffffff;
      --panel-2: #f4f4f2;
      --line: #e4e3df;
      --line-strong: #d3d2cc;
      --ink: #1c1c1a;
      --ink-dim: #6b6b64;
      --ink-faint: #9d9c95;
      --accent: #2f5eff;
      --accent-ink: #ffffff;
      --accent-soft: #eaeeff;
      --teal: #0ea88e;
      --teal-soft: #e3f7f2;
      --amber: #b8860b;
      --amber-soft: #fbf3de;
      --red: #d64545;
      --red-soft: #fbeaea;
      --radius: 12px;
      --disp: 'Space Grotesk', sans-serif;
      --body: 'IBM Plex Sans', sans-serif;
      --mono: 'IBM Plex Mono', monospace;
    }

    * { box-sizing: border-box; margin: 0; padding: 0; }

    body {
      background: var(--bg);
      color: var(--ink);
      font-family: var(--body);
    }

    ::selection { background: var(--accent-soft); color: var(--accent); }

    .wrap { max-width: 980px; margin: 0 auto; }

    .hero {
      display: flex;
      flex-direction: column;
      align-items: flex-start;
      gap: 6px;
      padding: 4px 4px 26px;
      border-bottom: 1px solid var(--line);
      margin-bottom: 30px;
    }

    .eyebrow {
      font-family: var(--mono);
      font-size: 11px;
      letter-spacing: 2.5px;
      color: var(--teal);
      text-transform: uppercase;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .eyebrow .dot { width: 6px; height: 6px; border-radius: 50%; background: var(--teal); }

    h1 {
      font-family: var(--disp);
      font-weight: 700;
      font-size: clamp(30px, 5vw, 42px);
      letter-spacing: -0.5px;
      line-height: 1.05;
      color: var(--ink);
    }

    .hero p {
      color: var(--ink-dim);
      font-size: 14.5px;
      max-width: 600px;
      margin-top: 6px;
      line-height: 1.55;
    }

    .engine-status {
      font-family: var(--mono);
      font-size: 11px;
      color: var(--ink-faint);
      margin-top: 14px;
      display: flex;
      align-items: center;
      gap: 7px;
    }

    .engine-status .pip { width: 6px; height: 6px; border-radius: 50%; background: var(--ink-faint); }
    .engine-status.ready .pip { background: var(--teal); }
    .engine-status.ready { color: var(--teal); }
    .engine-status.loading .pip { background: var(--accent); animation: pulse 1s infinite ease-in-out; }
    .engine-status.loading { color: var(--accent); }
    .engine-status.error .pip { background: var(--red); }
    .engine-status.error { color: var(--red); }

    @keyframes pulse { 0%,100% { opacity: 1; } 50% { opacity: 0.25; } }

    .dropzone {
      border: 1.5px dashed var(--line-strong);
      border-radius: var(--radius);
      padding: 64px 20px;
      text-align: center;
      cursor: pointer;
      transition: border-color .15s ease, background .15s ease;
      background: var(--panel);
    }

    .dropzone:hover, .dropzone.drag { border-color: var(--accent); background: var(--accent-soft); }

    .dropzone .icon {
      width: 52px; height: 52px; margin: 0 auto 16px; border-radius: 50%;
      background: var(--accent-soft); color: var(--accent);
      display: flex; align-items: center; justify-content: center; font-size: 22px;
    }

    .dropzone .main { font-family: var(--disp); font-size: 18px; font-weight: 600; color: var(--ink); }
    .dropzone .sub { font-size: 12px; color: var(--ink-faint); margin-top: 8px; font-family: var(--mono); letter-spacing: 0.3px; }

    #fileInput { display: none; }
    #uploadArea.hidden-big { display: none; }

    .top-actions { display: flex; justify-content: flex-end; margin-bottom: -6px; }

    .card {
      background: var(--panel);
      border: 1px solid var(--line);
      border-radius: var(--radius);
      padding: 22px 24px;
      margin-bottom: 18px;
      box-shadow: 0 1px 2px rgba(20, 20, 15, 0.03);
      display: none;
    }

    .card.visible { display: block; }
    .card h2 { font-family: var(--disp); font-size: 15px; font-weight: 600; margin-bottom: 16px; }

    /* file info */
    .meta-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
    @media (max-width: 520px) { .meta-grid { grid-template-columns: 1fr; } }

    .meta-item .label {
      font-family: var(--mono); font-size: 10.5px; letter-spacing: 1px; text-transform: uppercase;
      color: var(--ink-faint); margin-bottom: 4px;
    }
    .meta-item .value { font-family: var(--disp); font-size: 16px; font-weight: 600; word-break: break-word; }

    /* two-column settings row */
    .settings-row { display: grid; grid-template-columns: 1.15fr 1fr; gap: 26px; align-items: start; }
    @media (max-width: 780px) { .settings-row { grid-template-columns: 1fr; } }
    .settings-row h2 { margin-bottom: 16px; }

    /* waveform */
    .wave-scroll { overflow-x: auto; border: 1px solid var(--line); border-radius: 9px; background: var(--panel-2); position: relative; }
    canvas.wave-canvas { display: block; }

    .preview-controls { display: flex; align-items: center; gap: 10px; margin-top: 14px; flex-wrap: wrap; }
    .zoom-controls {
      margin-left: auto; display: flex; align-items: center; gap: 8px;
      font-family: var(--mono); font-size: 11.5px; color: var(--ink-faint);
    }

    .icon-btn {
      width: 34px; height: 34px; border-radius: 7px; border: 1px solid var(--line);
      background: var(--panel); color: var(--ink-dim); cursor: pointer;
      display: flex; align-items: center; justify-content: center; font-size: 15px;
      transition: all .12s ease; flex-shrink: 0;
    }
    .icon-btn:hover { border-color: var(--accent); color: var(--accent); }

    .legend { display: flex; align-items: center; gap: 16px; margin-top: 12px; font-size: 11.5px; color: var(--ink-faint); font-family: var(--mono); }
    .legend .swatch { width: 12px; height: 12px; border-radius: 3px; display: inline-block; margin-right: 6px; vertical-align: -2px; }
    .legend .swatch.keep { background: #c7d1ff; }
    .legend .swatch.cut { background: rgba(214, 69, 69, 0.35); border: 1px solid rgba(214, 69, 69, 0.6); }

    /* controls */
    .ctrl { margin-bottom: 20px; }
    .ctrl:last-child { margin-bottom: 0; }

    .ctrl label {
      display: flex; justify-content: space-between; align-items: baseline;
      font-family: var(--mono); font-size: 10.5px; letter-spacing: 1px; text-transform: uppercase;
      color: var(--ink-faint); margin-bottom: 10px;
    }
    .ctrl label .val { color: var(--accent); font-size: 12.5px; letter-spacing: 0; font-weight: 600; }

    input[type=range] {
      -webkit-appearance: none; width: 100%; height: 4px; border-radius: 2px;
      background: var(--line-strong); outline: none;
    }
    input[type=range]::-webkit-slider-thumb {
      -webkit-appearance: none; width: 15px; height: 15px; border-radius: 50%;
      background: var(--accent); cursor: pointer; border: 3px solid #fff; box-shadow: 0 0 0 1px var(--accent);
    }

    .preset-btns { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; margin-top: 12px; }
    @media (max-width: 420px) { .preset-btns { grid-template-columns: repeat(3, 1fr); } }

    .preset-btn {
      font-family: var(--mono); font-size: 11.5px; font-weight: 600; padding: 9px 6px;
      border-radius: 7px; border: 1px solid var(--line-strong); background: var(--panel);
      color: var(--ink); cursor: pointer; transition: all .12s ease; text-align: center;
    }
    .preset-btn:hover { border-color: var(--accent); color: var(--accent); }
    .preset-btn.active { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }

    .out-format { margin-top: 22px; }
    select.out-select {
      background: var(--panel-2); border: 1px solid var(--line); color: var(--ink);
      font-family: var(--mono); font-size: 12.5px; font-weight: 600;
      padding: 10px 12px; border-radius: 7px; cursor: pointer; width: 100%; max-width: 220px;
    }

    /* live stats */
    .stats-panel {
      background: var(--panel-2); border: 1px solid var(--line); border-radius: 9px;
      padding: 14px 16px; margin-top: 16px;
    }
    .stats-row {
      display: flex; justify-content: space-between; align-items: baseline;
      font-family: var(--mono); font-size: 12px; padding: 4px 0;
    }
    .stats-row .stat-label { color: var(--ink-faint); }
    .stats-row .stat-value { color: var(--ink); font-weight: 700; }
    .stats-row .stat-value.cut { color: var(--red); }

    .info-box, .warn-box {
      font-size: 12.5px; line-height: 1.55; padding: 14px 16px; border-radius: 9px; margin-top: 16px;
    }
    .info-box { background: var(--accent-soft); color: #1e3a8f; }
    .info-box strong { color: var(--accent); }
    .warn-box { background: var(--amber-soft); color: #7a5c00; border: 1px solid rgba(184, 134, 11, 0.25); }

    .btn {
      font-family: var(--mono); font-size: 12.5px; font-weight: 700; letter-spacing: 0.4px;
      padding: 13px 22px; border-radius: 8px; border: none; background: var(--accent); color: var(--accent-ink);
      cursor: pointer; transition: all .12s ease; display: inline-flex; align-items: center;
      gap: 8px; width: 100%; justify-content: center; margin-top: 20px;
    }
    .btn:hover { filter: brightness(1.07); }
    .btn:disabled { opacity: 0.45; cursor: not-allowed; }
    .btn.ghost {
      background: transparent; color: var(--ink-dim); border: 1px solid var(--line-strong);
      font-weight: 600; width: auto; margin-top: 0;
    }
    .btn.ghost:hover { border-color: var(--red); color: var(--red); }

    .bar { height: 4px; background: var(--line); border-radius: 2px; margin-top: 16px; overflow: hidden; display: none; }
    .bar.show { display: block; }
    .bar > i { display: block; height: 100%; width: 0%; background: linear-gradient(90deg, var(--teal), var(--accent)); transition: width .15s ease; }

    .status-line {
      display: none; align-items: center; justify-content: space-between; margin-top: 12px;
      font-family: var(--mono); font-size: 11.5px; color: var(--ink-faint);
    }
    .status-line.show { display: flex; }
    .status-tag { padding: 3px 8px; border-radius: 20px; text-transform: uppercase; letter-spacing: 0.5px; }
    .status-tag.error { background: var(--red-soft); color: var(--red); }
    .status-tag.done { background: var(--teal-soft); color: var(--teal); }

    /* result card */
    .result-header {
      display: flex; align-items: flex-start; justify-content: space-between;
      gap: 16px; margin-bottom: 18px; flex-wrap: wrap;
    }
    .result-heading .status-pill {
      display: flex; align-items: center; gap: 7px; font-family: var(--mono); font-size: 11px;
      font-weight: 600; color: var(--teal); text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 6px;
    }
    .result-heading .status-pill .pip { width: 7px; height: 7px; border-radius: 50%; background: var(--teal); }
    .result-heading h2 { font-family: var(--disp); font-size: 20px; font-weight: 700; margin-bottom: 0; }
    .btn.download-result { width: auto; margin-top: 0; background: var(--teal); padding: 12px 20px; flex-shrink: 0; }
    .btn.download-result:hover { filter: brightness(1.05); }

    .result-body { display: grid; grid-template-columns: 1.6fr 1fr; gap: 20px; align-items: stretch; }
    @media (max-width: 720px) { .result-body { grid-template-columns: 1fr; } }

    .result-side {
      background: var(--panel-2); border: 1px solid var(--line); border-radius: 9px;
      padding: 16px 18px; display: flex; flex-direction: column; gap: 14px;
    }
    .file-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
    .file-pair .label {
      font-family: var(--mono); font-size: 10.5px; letter-spacing: 1px; text-transform: uppercase;
      color: var(--ink-faint); margin-bottom: 4px;
    }
    .file-pair .fname { font-size: 13px; font-weight: 600; word-break: break-word; line-height: 1.4; }
    .result-info-box {
      background: var(--accent-soft); color: #1e3a8f; font-size: 12.5px; line-height: 1.55;
      padding: 12px 14px; border-radius: 8px;
    }

    .log-toggle {
      font-family: var(--mono); font-size: 11px; color: var(--ink-faint); background: none; border: none;
      cursor: pointer; margin-top: 22px; text-decoration: underline dotted;
    }
    .log-toggle:hover { color: var(--accent); }

    #log {
      display: none; background: var(--panel-2); border: 1px solid var(--line); border-radius: var(--radius);
      margin-top: 10px; padding: 12px 14px; height: 140px; overflow-y: auto;
      font-family: var(--mono); font-size: 10.5px; line-height: 1.6; color: #3a3a35; white-space: pre-wrap;
    }