:root {
    --bg: #f6f7f9;
    --surface: #ffffff;
    --surface-2: #f9fafb;
    --border: #e3e6ea;
    --border-strong: #cfd5dc;
    --text: #14181d;
    --muted: #667085;
    --accent: #4f46e5;
    --accent-soft: #eef2ff;
    --danger: #c02626;
    --ok: #067647;
    --radius: 12px;
    --shadow: 0 1px 2px rgba(16,24,40,.04), 0 1px 3px rgba(16,24,40,.06);
  }
  @media (prefers-color-scheme: dark) {
    :root {
      --bg: #0f1115;
      --surface: #171a21;
      --surface-2: #1c2028;
      --border: #272c35;
      --border-strong: #353b46;
      --text: #e8eaee;
      --muted: #98a2b3;
      --accent: #8b87f7;
      --accent-soft: #211f3a;
      --danger: #f97066;
      --ok: #47cd89;
      --shadow: 0 1px 2px rgba(0,0,0,.3);
    }
  }
  * { box-sizing: border-box; }
  html, body { margin: 0; padding: 0; }
  body {
    background: var(--bg);
    color: var(--text);
    font: 15px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
          "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    -webkit-font-smoothing: antialiased;
  }
  .wrap { max-width: 1020px; margin: 0 auto; padding: 0 20px 64px; }

  /* ---------- 顶栏 ---------- */
  header {
    display: flex; align-items: center; justify-content: space-between;
    gap: 16px; padding: 20px 0 16px;
    border-bottom: 1px solid var(--border); margin-bottom: 26px;
  }
  .brand { display: flex; align-items: center; gap: 10px; }
  .brand .mark {
    width: 30px; height: 30px; border-radius: 8px; background: var(--accent);
    display: grid; place-items: center; color: #fff; font-weight: 700; font-size: 13px;
    letter-spacing: .3px;
  }
  .brand b { font-size: 17px; letter-spacing: -.2px; }
  .badge {
    font-size: 12px; color: var(--ok); background: color-mix(in srgb, var(--ok) 12%, transparent);
    border: 1px solid color-mix(in srgb, var(--ok) 25%, transparent);
    padding: 2px 8px; border-radius: 999px; white-space: nowrap;
  }
  .headtools { display: flex; align-items: center; gap: 8px; }
  .chip {
    font-size: 13px; border: 1px solid var(--border-strong); background: var(--surface);
    color: var(--text); padding: 7px 13px; border-radius: 999px; cursor: pointer;
    display: inline-flex; align-items: center; gap: 7px; transition: .15s;
    font-family: inherit; line-height: 1.2;
  }
  .chip:hover { border-color: var(--accent); color: var(--accent); }
  .chip.pro { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
  #langBtn { min-width: 62px; justify-content: center; color: var(--muted); }

  /* ---------- 拖拽区 ---------- */
  .drop {
    border: 1.5px dashed var(--border-strong); border-radius: var(--radius);
    background: var(--surface); padding: 30px 20px; text-align: center;
    transition: .15s; cursor: pointer;
  }
  .drop:hover, .drop.over { border-color: var(--accent); background: var(--accent-soft); }
  .drop h1 { font-size: 19px; margin: 0 0 6px; letter-spacing: -.2px; }
  .drop p { margin: 6px 0 0; color: var(--muted); font-size: 13px; }
  .btn {
    border: 1px solid var(--border-strong); background: var(--surface); color: var(--text);
    padding: 8px 14px; border-radius: 9px; font-size: 14px; cursor: pointer;
    font-family: inherit; transition: .15s;
  }
  .btn:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }
  .btn:disabled { opacity: .5; cursor: not-allowed; }
  .btn.primary {
    background: var(--accent); border-color: var(--accent); color: #fff; font-weight: 600;
    padding: 11px 18px; width: 100%; font-size: 15px;
  }
  .btn.primary:hover:not(:disabled) { filter: brightness(1.07); color: #fff; }
  .btn.ghost { border-color: transparent; background: transparent; color: var(--muted); padding: 4px 7px; }
  .btn.ghost:hover { color: var(--danger); background: transparent; }

  /* ---------- 工作区 ---------- */
  .workspace { display: grid; grid-template-columns: 1fr 366px; gap: 20px; margin-top: 22px; }
  @media (max-width: 820px) { .workspace { grid-template-columns: 1fr; } }
  .card {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    box-shadow: var(--shadow);
  }
  .card > h2 {
    font-size: 13px; text-transform: uppercase; letter-spacing: .06em; color: var(--muted);
    margin: 0; padding: 14px 16px; border-bottom: 1px solid var(--border);
    display: flex; justify-content: space-between; align-items: center; font-weight: 600;
  }
  .card > h2 span { font-weight: 400; text-transform: none; letter-spacing: 0; }

  #fileList { list-style: none; margin: 0; padding: 6px; min-height: 60px; }
  #fileList li {
    display: flex; align-items: center; gap: 10px; padding: 9px 10px; border-radius: 9px;
    border: 1px solid transparent;
  }
  #fileList li + li { border-top: 1px solid var(--border); border-radius: 0; }
  #fileList .idx {
    font-size: 12px; color: var(--muted); width: 18px; text-align: right; flex: none;
    font-variant-numeric: tabular-nums;
  }
  #fileList .meta { min-width: 0; flex: 1; }
  #fileList .name {
    display: block; font-size: 14px; white-space: nowrap; overflow: hidden;
    text-overflow: ellipsis;
  }
  #fileList .sub { font-size: 12px; color: var(--muted); }
  #fileList .move { display: flex; gap: 2px; }
  .empty { color: var(--muted); font-size: 13px; text-align: center; padding: 22px 10px; }

  /* ---------- 操作面板 ---------- */
  .ops { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; padding: 14px 16px 4px; }
  .ops label {
    border: 1px solid var(--border); border-radius: 9px; padding: 9px 10px; cursor: pointer;
    font-size: 13px; line-height: 1.3; transition: .15s; display: block;
  }
  .ops label:hover { border-color: var(--border-strong); }
  .ops label.on { border-color: var(--accent); background: var(--accent-soft); }
  .ops input { display: none; }
  .ops b { display: block; font-weight: 600; font-size: 13.5px; }
  .ops small { color: var(--muted); font-size: 11.5px; }
  .ops .pro-tag {
    font-size: 10px; color: var(--accent); border: 1px solid var(--accent);
    border-radius: 4px; padding: 0 3px; margin-left: 4px; vertical-align: 1px;
  }

  .params { padding: 8px 16px 14px; display: grid; gap: 10px; }
  .field { display: grid; gap: 5px; }
  .field label { font-size: 12.5px; color: var(--muted); }
  .field input, .field select {
    font-family: inherit; font-size: 14px; padding: 8px 10px; border-radius: 8px;
    border: 1px solid var(--border-strong); background: var(--surface-2); color: var(--text);
  }
  .field input:focus, .field select:focus { outline: 2px solid var(--accent-soft); border-color: var(--accent); }
  .field .hint { font-size: 11.5px; color: var(--muted); }
  .row2 { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }

  .batchrow {
    margin: 0 16px 12px; padding: 10px 12px; border-radius: 9px; background: var(--surface-2);
    border: 1px solid var(--border); display: flex; align-items: center; gap: 9px;
    font-size: 13px; cursor: pointer;
  }
  .batchrow input { accent-color: var(--accent); }
  .batchrow .lock { margin-left: auto; font-size: 11px; color: var(--accent); }

  .panel .foot { padding: 0 16px 16px; }
  .barwrap { height: 5px; background: var(--border); border-radius: 99px; overflow: hidden; margin: 12px 0 8px; display: none; }
  .barwrap.on { display: block; }
  .bar { height: 100%; width: 0; background: var(--accent); transition: width .18s ease; }
  .progmsg { font-size: 12.5px; color: var(--muted); min-height: 18px; }

  /* ---------- 结果 ---------- */
  .results { margin-top: 22px; }
  #resultList { list-style: none; margin: 0; padding: 8px; display: grid; gap: 6px; }
  #resultList li {
    display: flex; align-items: center; gap: 12px; padding: 10px 12px;
    border: 1px solid var(--border); border-radius: 9px; background: var(--surface-2);
  }
  #resultList .name { flex: 1; font-size: 14px; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  #resultList .sub { font-size: 12px; color: var(--muted); white-space: nowrap; }
  #resultList a {
    font-size: 13px; text-decoration: none; color: var(--accent); border: 1px solid var(--accent);
    padding: 5px 11px; border-radius: 7px; white-space: nowrap;
  }
  #resultList a:hover { background: var(--accent-soft); }

  /* ---------- 弹窗 ---------- */
  .modal {
    position: fixed; inset: 0; background: rgba(9,12,18,.5); display: none;
    place-items: center; padding: 20px; z-index: 50;
  }
  .modal.on { display: grid; }
  .sheet {
    background: var(--surface); border-radius: 14px; padding: 24px; width: 100%;
    max-width: 430px; border: 1px solid var(--border); box-shadow: 0 12px 40px rgba(0,0,0,.22);
  }
  .sheet h3 { margin: 0 0 6px; font-size: 18px; }
  .sheet p { color: var(--muted); font-size: 13.5px; margin: 0 0 16px; }
  .sheet .field { margin-bottom: 12px; }
  .sheet .actions { display: flex; gap: 9px; margin-top: 4px; }
  .sheet .actions .btn { flex: 1; }
  .err { color: var(--danger); font-size: 12.5px; min-height: 17px; margin: 4px 0 0; }
  .buyline { margin-top: 16px; padding-top: 14px; border-top: 1px solid var(--border); font-size: 13px; color: var(--muted); }
  .buyline a { color: var(--accent); }

  /* ---------- 提示 ---------- */
  #toast {
    position: fixed; left: 50%; bottom: 26px; transform: translate(-50%, 14px);
    background: #14181d; color: #fff; padding: 10px 16px; border-radius: 9px; font-size: 13.5px;
    opacity: 0; pointer-events: none; transition: .2s; max-width: 90vw; text-align: center; z-index: 60;
  }
  #toast.on { opacity: 1; transform: translate(-50%, 0); }

  footer { margin-top: 40px; padding-top: 18px; border-top: 1px solid var(--border); color: var(--muted); font-size: 12.5px; display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
  footer a { color: var(--muted); }

/* ---------- SEO 落地页（/split-pdf-without-uploading） ---------- */
.hero { padding: 30px 0 18px; }
.hero h1 { font-size: 31px; line-height: 1.22; margin: 0 0 10px; letter-spacing: -.025em; }
.hero p { color: var(--muted); font-size: 16px; max-width: 64ch; margin: 0; }
@media (max-width: 640px) { .hero h1 { font-size: 25px; } .hero p { font-size: 15px; } }

.drop .dropTitle { font-weight: 600; font-size: 17px; margin: 0 0 4px; }

.prose { margin-top: 34px; }
.prose section { margin-top: 28px; }
.prose h2 { font-size: 20px; margin: 0 0 10px; letter-spacing: -.01em; }
.prose p { margin: 0 0 12px; max-width: 76ch; }
.prose .note {
  border-left: 3px solid var(--accent); padding: 2px 0 2px 12px;
  color: var(--muted); font-size: 14px; margin: 14px 0 0;
}
.steps { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); }
.step {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 13px 15px;
}
.step b { display: block; margin-bottom: 4px; font-size: 14.5px; }
.step span { color: var(--muted); font-size: 13.5px; }

.faq details { border-bottom: 1px solid var(--border); padding: 11px 0; }
.faq details:first-of-type { border-top: 1px solid var(--border); }
.faq summary { cursor: pointer; font-weight: 600; font-size: 14.5px; }
.faq details p { margin: 9px 0 0; color: var(--muted); font-size: 14px; }

.backlink { display: inline-block; margin-top: 26px; color: var(--accent); text-decoration: none; font-size: 14px; }
.backlink:hover { text-decoration: underline; }