:root {
  --bg: #eef2ff;
  --text: #111827;
  --muted: #6b7280;
  --line: rgba(17, 24, 39, 0.08);
  --glass: rgba(255, 255, 255, 0.62);
  --glass-strong: rgba(255, 255, 255, 0.82);
  --glass-border: rgba(255, 255, 255, 0.75);
  --shadow: 0 10px 40px rgba(31, 41, 99, 0.10);
  --primary: #4f46e5;
  --primary-2: #06b6d4;
  --primary-soft: rgba(79, 70, 229, 0.10);
  --ok: #059669;
  --err: #dc2626;
  --blob1: #a5b4fc;
  --blob2: #67e8f9;
  --blob3: #f9a8d4;
  --radius: 22px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1020;
    --text: #e5e7eb;
    --muted: #9ca3af;
    --line: rgba(255, 255, 255, 0.08);
    --glass: rgba(23, 28, 48, 0.62);
    --glass-strong: rgba(30, 36, 60, 0.85);
    --glass-border: rgba(255, 255, 255, 0.08);
    --shadow: 0 10px 40px rgba(0, 0, 0, 0.35);
    --primary: #818cf8;
    --primary-2: #22d3ee;
    --primary-soft: rgba(129, 140, 248, 0.14);
    --ok: #34d399;
    --err: #f87171;
    --blob1: #3730a3;
    --blob2: #155e75;
    --blob3: #831843;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.6 -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; }
.muted { color: var(--muted); }

/* 背景光斑 */
.bg { position: fixed; inset: 0; z-index: -1; overflow: hidden; }
.bg i { position: absolute; border-radius: 50%; filter: blur(80px); opacity: 0.55; }
.bg i:nth-child(1) { width: 520px; height: 520px; background: var(--blob1); top: -160px; left: -120px; }
.bg i:nth-child(2) { width: 460px; height: 460px; background: var(--blob2); top: 120px; right: -160px; }
.bg i:nth-child(3) { width: 420px; height: 420px; background: var(--blob3); bottom: -200px; left: 30%; opacity: 0.35; }

.glass {
  background: var(--glass);
  border: 1px solid var(--glass-border);
  box-shadow: var(--shadow);
  backdrop-filter: blur(22px) saturate(1.4);
  -webkit-backdrop-filter: blur(22px) saturate(1.4);
  border-radius: var(--radius);
}

/* 顶栏 */
.top {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; gap: 24px;
  padding: 14px max(16px, calc((100vw - 1080px) / 2));
  background: color-mix(in srgb, var(--bg) 70%, transparent);
  backdrop-filter: blur(18px); -webkit-backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; }
.brand-name { font-size: 20px; font-weight: 800; letter-spacing: 1px; }
.brand-domain { font-size: 12px; color: var(--muted); }
.nav { display: flex; gap: 20px; margin-left: auto; font-size: 14px; color: var(--muted); }
.nav a:hover { color: var(--text); }
.quota {
  font-size: 13px; padding: 4px 12px; border-radius: 99px;
  background: var(--primary-soft); color: var(--primary); white-space: nowrap;
}

main { max-width: 1080px; margin: 0 auto; padding: 0 16px; }

/* 首屏 */
.hero { padding: 56px 0 24px; text-align: center; }
h1 { font-size: clamp(30px, 5vw, 48px); line-height: 1.2; margin: 0 0 14px; letter-spacing: 1px; }
.grad { background: linear-gradient(90deg, var(--primary), var(--primary-2)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.sub { color: var(--muted); margin: 0 auto 28px; max-width: 620px; font-size: 16px; }

.mode-bar {
  display: inline-flex; gap: 12px; align-items: center; margin-bottom: 14px;
  padding: 6px 8px 6px 16px; border-radius: 99px; background: var(--primary-soft); color: var(--primary); font-size: 14px;
}
.link { background: none; border: 0; color: var(--muted); cursor: pointer; text-decoration: underline; font-size: 13px; }

.drop {
  display: flex; flex-direction: column; align-items: center; gap: 8px;
  padding: 44px 20px; cursor: pointer; transition: transform .15s, border-color .15s, background .15s;
  border: 2px dashed color-mix(in srgb, var(--primary) 30%, transparent);
  outline: none;
}
.drop:hover, .drop:focus-visible { border-color: var(--primary); }
.drop.over { transform: scale(1.01); border-color: var(--primary); background: var(--glass-strong); }
.drop-icon {
  width: 64px; height: 64px; border-radius: 20px; display: grid; place-items: center;
  color: #fff; background: linear-gradient(135deg, var(--primary), var(--primary-2));
  box-shadow: 0 8px 24px color-mix(in srgb, var(--primary) 35%, transparent);
}
.drop-title { font-size: 18px; font-weight: 600; }
.drop-title u { color: var(--primary); text-underline-offset: 4px; }
.drop-hint { color: var(--muted); font-size: 13px; }

/* 文件列表 */
.list { display: flex; flex-direction: column; gap: 10px; margin-top: 16px; text-align: left; }
.item { padding: 14px 16px; }
.item-row { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.ficon {
  flex: none; width: 42px; height: 42px; border-radius: 12px; display: grid; place-items: center;
  font-size: 11px; font-weight: 800; color: #fff; letter-spacing: .5px;
}
.ficon.word { background: #2563eb; } .ficon.sheet { background: #16a34a; } .ficon.slide { background: #ea580c; }
.ficon.pdf { background: #dc2626; } .ficon.image { background: #9333ea; } .ficon.audio { background: #db2777; }
.ficon.video { background: #0891b2; } .ficon.unknown { background: #6b7280; }
.fmeta { flex: 1 1 200px; min-width: 0; }
.fname { font-weight: 600; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.fsize { font-size: 12px; color: var(--muted); }
.arrow { color: var(--muted); }
.badge { display: inline-block; margin-left: 6px; padding: 0 8px; border-radius: 99px; font-size: 11px; line-height: 18px; vertical-align: 1px; }
.badge.local { background: color-mix(in srgb, var(--ok) 14%, transparent); color: var(--ok); }
.badge.server { background: var(--primary-soft); color: var(--primary); }
a.btn { display: inline-block; }
select, input[type="number"] {
  font: inherit; color: var(--text); background: var(--glass-strong);
  border: 1px solid var(--line); border-radius: 12px; padding: 7px 10px; min-width: 0;
}
select:focus, input:focus { outline: 2px solid color-mix(in srgb, var(--primary) 40%, transparent); }
.item-actions { display: flex; gap: 8px; align-items: center; }

.btn {
  border: 0; border-radius: 12px; padding: 8px 16px; cursor: pointer; font-weight: 600; white-space: nowrap;
  transition: transform .1s, opacity .15s;
}
.btn:active { transform: scale(.97); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn.primary { color: #fff; background: linear-gradient(135deg, var(--primary), var(--primary-2)); }
.btn.ok { color: #fff; background: var(--ok); }
.btn.ghost { background: var(--glass-strong); border: 1px solid var(--line); }
.icon-btn {
  border: 0; background: transparent; color: var(--muted); cursor: pointer; width: 32px; height: 32px; border-radius: 10px;
  display: grid; place-items: center;
}
.icon-btn:hover { background: var(--primary-soft); color: var(--text); }

.status { margin-top: 10px; font-size: 13px; color: var(--muted); display: flex; align-items: center; gap: 10px; }
.status.err { color: var(--err); }
.status.ok { color: var(--ok); }
.bar { flex: 1; height: 6px; border-radius: 99px; background: var(--line); overflow: hidden; }
.bar > i { display: block; height: 100%; width: 0; border-radius: 99px; background: linear-gradient(90deg, var(--primary), var(--primary-2)); transition: width .4s; }
.bar.indeterminate > i { width: 30% !important; animation: slide 1.2s infinite ease-in-out; }
@keyframes slide { from { transform: translateX(-100%); } to { transform: translateX(340%); } }

.opts { margin-top: 12px; padding-top: 12px; border-top: 1px dashed var(--line); display: flex; flex-wrap: wrap; gap: 14px 22px; font-size: 13px; }
.opts label { display: flex; align-items: center; gap: 8px; color: var(--muted); }
.opts input[type="range"] { width: 120px; accent-color: var(--primary); }
.opts input[type="number"] { width: 100px; }

.list-actions { display: flex; justify-content: center; gap: 10px; margin-top: 14px; }

/* PDF 合并 */
.merge { margin-top: 16px; padding: 18px; text-align: left; }
.merge-head { display: flex; gap: 12px; align-items: baseline; flex-wrap: wrap; margin-bottom: 10px; }
.merge-list { margin: 0; padding: 0; list-style: none; display: flex; flex-direction: column; gap: 6px; counter-reset: m; }
.merge-list li {
  counter-increment: m; display: flex; align-items: center; gap: 10px; padding: 8px 10px;
  border-radius: 12px; background: var(--glass-strong); border: 1px solid var(--line);
}
.merge-list li::before { content: counter(m); width: 22px; text-align: center; color: var(--muted); font-size: 13px; }
.merge-list .fname { flex: 1; }
.merge-list li.muted::before { content: none; }
.merge-foot { display: flex; gap: 10px; justify-content: flex-end; margin-top: 12px; flex-wrap: wrap; }

/* 区块 */
.section { padding: 40px 0 8px; }
h2 { font-size: 24px; margin: 0 0 18px; }
.tools { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(220px, 100%), 1fr)); gap: 12px; }
.tool {
  text-align: left; padding: 16px; cursor: pointer; border: 1px solid var(--glass-border);
  display: flex; gap: 12px; align-items: flex-start; transition: transform .15s, box-shadow .15s;
}
.tool:hover { transform: translateY(-2px); box-shadow: 0 14px 40px color-mix(in srgb, var(--primary) 18%, transparent); }
.tool b { display: block; font-size: 15px; }
.tool span { font-size: 13px; color: var(--muted); }
.tool .ficon { width: 38px; height: 38px; font-size: 10px; }

.formats { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(300px, 100%), 1fr)); gap: 12px; }
.fmt { padding: 16px 18px; }
.fmt b { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; }
.fmt .dot { width: 10px; height: 10px; border-radius: 4px; }
.fmt p { margin: 4px 0; font-size: 13px; color: var(--muted); word-break: break-word; }
.fmt p em { font-style: normal; color: var(--text); }

.faq { display: flex; flex-direction: column; gap: 10px; }
.faq details { padding: 14px 18px; border-radius: 16px; }
.faq summary { cursor: pointer; font-weight: 600; }
.faq p { margin: 10px 0 2px; color: var(--muted); }

.foot {
  max-width: 1080px; margin: 48px auto 0; padding: 24px 16px 36px; border-top: 1px solid var(--line);
  display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; font-size: 13px;
}

.toast {
  position: fixed; left: 50%; bottom: 28px; transform: translate(-50%, 20px); opacity: 0; pointer-events: none;
  padding: 10px 18px; border-radius: 12px; background: var(--text); color: var(--bg); font-size: 14px;
  transition: opacity .2s, transform .2s; max-width: calc(100vw - 32px); z-index: 50;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

@media (max-width: 640px) {
  .nav { display: none; }
  .quota { margin-left: auto; }
  .brand-domain { display: none; }
  .hero { padding-top: 32px; }
  .drop { padding: 32px 16px; }
  .item-row select { flex: 1; }
}