: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: 580px;
      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 { display: none; 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 */
    .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 information grid */
    .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: preview | normalization settings */
    .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 preview */
    .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;
    }

    .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); }

    /* mode tabs */
    .mode-tabs {
      display: grid;
      grid-template-columns: 1fr 1fr 1fr;
      gap: 8px;
      margin-bottom: 20px;
    }

    .mode-tab {
      font-family: var(--mono);
      font-size: 12px;
      font-weight: 700;
      letter-spacing: 0.4px;
      padding: 10px 8px;
      border-radius: 8px;
      border: 1px solid var(--line-strong);
      background: var(--panel);
      color: var(--ink-dim);
      cursor: pointer;
      transition: all .12s ease;
      text-align: center;
    }

    .mode-tab:hover { border-color: var(--accent); color: var(--accent); }

    .mode-tab.active {
      background: var(--accent);
      border-color: var(--accent);
      color: var(--accent-ink);
    }

    /* target level control */
    .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;
      line-height: 1.3;
    }

    .preset-btn:hover { border-color: var(--accent); color: var(--accent); }

    .preset-btn.active {
      background: var(--accent);
      border-color: var(--accent);
      color: var(--accent-ink);
    }

    .mode-hint {
      font-size: 11.5px;
      color: var(--ink-faint);
      margin-top: 12px;
      line-height: 1.55;
    }

    .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;
    }

    .info-box, .warn-box, .hint-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); }

    /* progress + result */
    .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;
    }

    .loudness-pair {
      display: grid;
      grid-template-columns: 1fr auto 1fr;
      gap: 8px;
      align-items: center;
      background: var(--panel);
      border: 1px solid var(--line);
      border-radius: 8px;
      padding: 10px 12px;
    }

    .loudness-pair .lp-item { text-align: center; }
    .loudness-pair .lp-item .label {
      font-family: var(--mono);
      font-size: 9.5px;
      letter-spacing: 0.8px;
      text-transform: uppercase;
      color: var(--ink-faint);
      margin-bottom: 3px;
    }
    .loudness-pair .lp-item .value {
      font-family: var(--disp);
      font-weight: 700;
      font-size: 15px;
    }
    .loudness-pair .arrow {
      color: var(--ink-faint);
      font-size: 14px;
    }

    .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 {
      display: none;
      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;
    }