:root {
  --bg: #0f1115;
  --card: #1a1d24;
  --line: #2a2f3a;
  --txt: #e8eaf0;
  --muted: #9aa3b2;
  --accent: #4f9dff;
  --accent2: #2f7be0;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--txt);
  line-height: 1.5;
}
header { text-align: center; padding: 28px 16px 8px; }
header h1 { margin: 0; font-size: 26px; letter-spacing: 1px; }
.sub { color: var(--muted); margin: 6px 0; }
.privacy { color: #ffcf6b; font-size: 13px; margin: 4px 0; }
main {
  max-width: 960px; margin: 0 auto; padding: 16px;
  display: grid; grid-template-columns: 1fr; gap: 18px;
}
@media (min-width: 820px) {
  main { grid-template-columns: 360px 1fr; align-items: start; }
}
.panel, .preview-wrap {
  background: var(--card); border: 1px solid var(--line);
  border-radius: 12px; padding: 18px;
}
.drop {
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 6px; border: 2px dashed var(--line); border-radius: 10px;
  padding: 26px 12px; text-align: center; cursor: pointer; color: var(--muted);
  transition: border-color .15s, color .15s;
}
.drop:hover, .drop.over { border-color: var(--accent); color: var(--txt); }
.drop small { font-size: 12px; opacity: .7; }
.filelist { margin: 12px 0; font-size: 13px; color: var(--muted); }
.filelist div { padding: 3px 0; border-bottom: 1px solid var(--line); }
.opts { margin: 10px 0; font-size: 14px; display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.opts label { cursor: pointer; }
.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 8px; }
button {
  background: var(--accent2); color: #fff; border: 0; border-radius: 8px;
  padding: 10px 16px; font-size: 14px; cursor: pointer; transition: background .15s;
}
button:hover:not(:disabled) { background: var(--accent); }
button:disabled { opacity: .4; cursor: not-allowed; }
button.ghost { background: transparent; border: 1px solid var(--line); color: var(--muted); }
.progress { margin-top: 10px; font-size: 13px; color: var(--accent); min-height: 18px; }
.preview-wrap h2 { margin: 0 0 12px; font-size: 18px; }
.preview { display: flex; flex-direction: column; gap: 14px; }
.preview canvas {
  width: 100%; height: auto; background: #fff; border-radius: 6px;
  border: 1px solid var(--line);
}
.preview .pageno { font-size: 12px; color: var(--muted); margin-top: -8px; }
footer { text-align: center; color: var(--muted); font-size: 12px; padding: 20px; }