:root {
  color-scheme: light;
  --bg: #f2f5fa;
  --card: #ffffff;
  --fg: #111827;
  --muted: #64748b;
  --line: #e2e8f0;
  --line-strong: #cbd5e1;
  --surface-2: #f8fafc;
  --surface-3: #f1f5f9;
  --surface-4: #e2e8f0;
  --text-strong: #334155;
  --text-soft: #475569;
  --brand: #2563eb;
  --brand-dark: #1d4ed8;
  --brand-text: #1d4ed8;
  --brand-soft: #eff6ff;
  --brand-line: #bfdbfe;
  --focus: #dbeafe;
  --ok-soft: #ecfdf5;
  --ok-line: #a7f3d0;
  --warn-soft: #fffbeb;
  --warn-line: #fde68a;
  --warn-text: #78350f;
  --warn-strong: #92400e;
  --danger: #b91c1c;
  --danger-soft: #fef2f2;
  --danger-line: #fecaca;
  --danger-input: #fca5a5;
  --invalid-ring: #fee2e2;
  --drop-bg: #fbfdff;
  --field: #ffffff;
  --body-glow: #dbeafe;
  --body-glow-0: rgba(219, 234, 254, 0);
  --radius: 16px;
  --shadow:
    0 1px 2px rgba(15, 23, 42, 0.04), 0 12px 32px -20px rgba(15, 23, 42, 0.35);
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --bg: #0b1220;
    --card: #111c2e;
    --fg: #e6edf7;
    --muted: #93a4bb;
    --line: #26364d;
    --line-strong: #3b4d66;
    --surface-2: #162337;
    --surface-3: #1d2c42;
    --surface-4: #273850;
    --text-strong: #d7e2f0;
    --text-soft: #b4c2d6;
    --brand: #2563eb;
    --brand-dark: #1d4ed8;
    --brand-text: #93c5fd;
    --brand-soft: #162b4a;
    --brand-line: #2c4f7c;
    --focus: #1e3a5f;
    --ok-soft: #102a25;
    --ok-line: #245c4c;
    --warn-soft: #2a2213;
    --warn-line: #5c4a1f;
    --warn-text: #f6d58a;
    --warn-strong: #fde7b0;
    --danger: #f87171;
    --danger-soft: #2d161a;
    --danger-line: #6b2b33;
    --danger-input: #b4545c;
    --invalid-ring: rgba(248, 113, 113, 0.18);
    --drop-bg: #101c2e;
    --field: #0f1a2b;
    --body-glow: #16345a;
    --body-glow-0: rgba(22, 52, 90, 0);
    --shadow:
      0 1px 2px rgba(0, 0, 0, 0.35), 0 18px 44px -24px rgba(0, 0, 0, 0.8);
  }
}

* {
  box-sizing: border-box;
}
html,
body {
  margin: 0;
}
body {
  background:
    radial-gradient(
      1100px 420px at 50% -240px,
      var(--body-glow) 0%,
      var(--body-glow-0) 70%
    ),
    var(--bg);
  color: var(--fg);
  font:
    15px/1.65 system-ui,
    -apple-system,
    'Segoe UI',
    'Microsoft YaHei',
    'PingFang SC',
    'Hiragino Sans GB',
    sans-serif;
  -webkit-font-smoothing: antialiased;
}
.app {
  max-width: 900px;
  margin: 0 auto;
  padding: 40px 20px 80px;
}
.hero {
  margin-bottom: 26px;
}
.hero h1 {
  margin: 0 0 8px;
  font-size: 29px;
  line-height: 1.3;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 11px;
}
.hero h1 .hero-icon {
  width: 30px;
  height: 30px;
  flex: none;
}
.hero p {
  margin: 0;
  color: var(--muted);
  max-width: 64ch;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 24px;
  margin-bottom: 18px;
  box-shadow: var(--shadow);
}
.card > h2 {
  margin: 0 0 16px;
  font-size: 17px;
  letter-spacing: -0.01em;
  display: flex;
  align-items: center;
  gap: 10px;
}
.n {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: none;
  width: 25px;
  height: 25px;
  border-radius: 50%;
  background: var(--brand);
  color: #fff;
  font-size: 13px;
  font-weight: 700;
  font-style: normal;
}
.hint {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.6;
}
.hint b {
  color: var(--text-strong);
}
#pdfHint b {
  white-space: nowrap;
}
.row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 14px;
}

/* ---------- 文件选择 ---------- */
.drop {
  border: 2px dashed var(--line-strong);
  border-radius: 14px;
  padding: 26px 20px;
  text-align: center;
  background: var(--drop-bg);
  transition: 0.18s ease;
  cursor: pointer;
}
.drop:hover,
.drop:focus-visible {
  border-color: var(--brand);
  background: var(--brand-soft);
  outline: none;
}
.drop.over {
  border-color: var(--brand);
  background: var(--brand-soft);
  transform: translateY(-1px);
}
.drop .row {
  justify-content: center;
  margin-top: 0;
}
.drop p {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 13px;
}
.file-info {
  margin-top: 14px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 14px;
  padding: 12px 14px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px solid var(--line);
  font-size: 14px;
}
.file-info b {
  font-weight: 600;
  word-break: break-all;
}
.file-info span {
  color: var(--muted);
  font-size: 13px;
}

/* ---------- 按钮 ---------- */
.btn {
  appearance: none;
  border: 1px solid transparent;
  border-radius: 11px;
  cursor: pointer;
  font: inherit;
  font-weight: 600;
  padding: 10px 18px;
  background: var(--surface-3);
  color: var(--fg);
  transition: 0.15s;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}
.btn:hover {
  background: var(--surface-4);
}
.btn:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 1px;
}
.btn.primary {
  background: var(--brand);
  color: #fff;
}
.btn.primary:hover {
  background: var(--brand-dark);
}
.btn.ghost {
  background: var(--card);
  border-color: var(--line);
  color: var(--text-strong);
}
.btn.ghost:hover {
  background: var(--surface-2);
}
.btn.lg {
  padding: 13px 24px;
  font-size: 15px;
  width: 100%;
}
.btn:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

/* ---------- 表单 ---------- */
.fields {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 14px;
}
.field {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-strong);
}
.field input,
.field select {
  font: inherit;
  font-weight: 400;
  padding: 9px 11px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: var(--field);
  color: var(--fg);
  width: 100%;
}
.field input:focus,
.field select:focus {
  outline: none;
  border-color: var(--brand);
  box-shadow: 0 0 0 3px var(--focus);
}
.field input.invalid {
  border-color: var(--danger-input);
  box-shadow: 0 0 0 3px var(--invalid-ring);
}
.checks {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  margin-top: 16px;
}
.check {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13.5px;
  cursor: pointer;
  color: var(--text-strong);
}
.check input {
  width: 17px;
  height: 17px;
  accent-color: var(--brand);
  cursor: pointer;
}
.check b {
  color: var(--fg);
}
.plan-hint {
  margin: 14px 0 0;
  padding: 11px 13px;
  border-radius: 11px;
  background: var(--surface-2);
  border: 1px solid var(--line);
  font-size: 13px;
  color: var(--text-soft);
  line-height: 1.7;
}
.plan-hint.err {
  background: var(--danger-soft);
  border-color: var(--danger-line);
  color: var(--danger);
}

/* ---------- 打印步骤 ---------- */
.warn {
  display: flex;
  gap: 10px;
  margin: 0 0 18px;
  padding: 12px 14px;
  border-radius: 12px;
  background: var(--warn-soft);
  border: 1px solid var(--warn-line);
  color: var(--warn-text);
  font-size: 13.5px;
  line-height: 1.65;
}
.warn .warn-icon {
  width: 18px;
  height: 18px;
  flex: none;
  margin-top: 3px;
}
.warn b {
  color: var(--warn-strong);
}
.pass {
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 16px 18px;
  margin-bottom: 12px;
  background: var(--card);
  transition: 0.18s ease;
}
.pass.done {
  border-color: var(--ok-line);
  background: var(--ok-soft);
}
.pass.active {
  border-color: var(--brand-line);
  box-shadow: 0 0 0 4px var(--focus);
}
.pass h3 {
  margin: 0 0 8px;
  font-size: 15px;
}
.pages {
  margin: 0 0 12px;
  font-size: 13.5px;
  color: var(--text-strong);
  line-height: 1.75;
  font-variant-numeric: tabular-nums;
  word-break: break-word;
}

/* ---------- 翻面提示对话框 ---------- */
.flip-dialog {
  width: min(92vw, 460px);
  max-width: calc(100vw - 32px);
  margin: auto;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--card);
  color: var(--fg);
  box-shadow: 0 24px 80px -28px rgba(15, 23, 42, 0.55);
}
.flip-dialog::backdrop {
  background: rgba(15, 23, 42, 0.55);
  backdrop-filter: blur(2px);
}
@media (prefers-color-scheme: dark) {
  .flip-dialog::backdrop {
    background: rgba(0, 0, 0, 0.68);
  }
}
.dialog-body {
  padding: 24px 24px 22px;
}
.dialog-kicker {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--brand-text);
  margin-bottom: 8px;
}
.flip-dialog h2 {
  margin: 0 0 10px;
  font-size: 20px;
  line-height: 1.35;
  letter-spacing: -0.01em;
}
.dialog-text {
  margin: 0;
  color: var(--text-soft);
  font-size: 14px;
  line-height: 1.7;
}
.dialog-text b {
  color: var(--fg);
}
.dialog-note {
  margin: 12px 0 0;
  padding: 10px 12px;
  border-radius: 10px;
  background: var(--surface-2);
  border: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
  line-height: 1.6;
}
.dialog-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 10px;
  margin-top: 20px;
}
@media (max-width: 480px) {
  .dialog-body {
    padding: 20px 18px 18px;
  }
  .dialog-actions .btn {
    flex: 1 1 140px;
  }
}

/* ---------- 进度 / 错误 ---------- */
.progress {
  margin-top: 14px;
}
.bar {
  height: 6px;
  border-radius: 99px;
  background: var(--surface-4);
  overflow: hidden;
}
.bar span {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, #3b82f6, #6366f1);
  transition: width 0.2s;
}
.error {
  margin: 14px 0 0;
  padding: 11px 13px;
  border-radius: 11px;
  background: var(--danger-soft);
  border: 1px solid var(--danger-line);
  color: var(--danger);
  font-size: 13.5px;
}

/* ---------- 帮助 ---------- */
.steps {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: s;
}
.steps li {
  position: relative;
  padding: 0 0 18px 40px;
  counter-increment: s;
}
.steps li:not(:last-child)::after {
  content: '';
  position: absolute;
  left: 12px;
  top: 26px;
  bottom: 2px;
  width: 2px;
  background: var(--line);
}
.steps li::before {
  content: counter(s);
  position: absolute;
  left: 0;
  top: 1px;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--brand-soft);
  color: var(--brand-text);
  border: 1px solid var(--brand-line);
  font-size: 12.5px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}
.steps > li > b {
  display: block;
  margin-bottom: 2px;
}
.steps p {
  margin: 0;
  color: var(--muted);
  font-size: 13.5px;
}
details {
  border-top: 1px solid var(--line);
  padding: 12px 0 0;
  margin-top: 6px;
}
details:first-of-type {
  border-top: 0;
  padding-top: 0;
  margin-top: 0;
}
summary {
  cursor: pointer;
  font-weight: 600;
  font-size: 14px;
  padding: 4px 0;
  list-style: none;
}
summary::-webkit-details-marker {
  display: none;
}
summary::before {
  content: '＋';
  display: inline-block;
  width: 18px;
  color: var(--brand-text);
  font-weight: 700;
}
details[open] summary::before {
  content: '－';
}
details p {
  margin: 6px 0 0 18px;
  color: var(--muted);
  font-size: 13.5px;
}
[hidden] {
  display: none !important;
}

@media (max-width: 560px) {
  .app {
    padding: 24px 14px 60px;
  }
  .card {
    padding: 18px 16px;
  }
  .hero h1 {
    font-size: 23px;
  }
}