:root {
  --bg: #f3f4f6;
  --card: #ffffff;
  --text: #1f2937;
  --text-secondary: #6b7280;
  --text-tertiary: #9ca3af;
  --primary: #2563eb;
  --primary-light: #eff6ff;
  --primary-border: #bfdbfe;
  --border: #e5e7eb;
  --border-dashed: #d1d5db;
  --success: #10b981;
  --warning: #f59e0b;
  --error: #dc2626;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.05), 0 1px 2px rgba(0, 0, 0, 0.03);
  --shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.06);
  --radius: 16px;
  --radius-sm: 12px;
}

* { box-sizing: border-box; }

/* 旧版提示条：告知用户可前往新版 */
.legacy-banner{
  background:#1f2937;color:#e5e7eb;font:14px/1.5 -apple-system,"Segoe UI","Microsoft YaHei",sans-serif;
  text-align:center;padding:9px 14px;border-bottom:1px solid rgba(255,255,255,.08);
}
.legacy-banner strong{color:#fff;font-weight:600}
.legacy-banner a{color:#7dd3fc;text-decoration:underline;font-weight:600}
.legacy-banner a:hover{color:#bae6fd}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  padding: 40px 16px 60px;
}

.container {
  max-width: 720px;
  margin: 0 auto;
}

header {
  text-align: center;
  margin-bottom: 24px;
}

h1 {
  font-size: 28px;
  font-weight: 700;
  margin: 0 0 8px;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 15px;
  margin: 0;
}

.card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
  margin-bottom: 16px;
}

.upload-zone {
  border: 2px dashed var(--border-dashed);
  border-radius: var(--radius);
  padding: 48px 24px;
  text-align: center;
  cursor: pointer;
  transition: all 0.2s ease;
  position: relative;
  overflow: hidden;
}

.upload-zone:hover,
.upload-zone.dragover {
  border-color: var(--primary);
  background: var(--primary-light);
  transform: scale(1.01);
}

.upload-zone input[type="file"] {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
  width: 100%;
  height: 100%;
}

.upload-icon {
  width: 48px;
  height: 48px;
  color: var(--text-tertiary);
  margin-bottom: 12px;
}

.upload-title {
  font-size: 17px;
  font-weight: 500;
  color: var(--text);
  margin: 0 0 6px;
}

.upload-hint {
  font-size: 13px;
  color: var(--text-secondary);
  margin: 0;
}

.section-title {
  font-size: 16px;
  font-weight: 600;
  margin: 0 0 14px;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
}

.batch-progress {
  font-size: 13px;
  font-weight: 500;
  color: var(--primary);
}

.presets {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 16px;
}

.preset {
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 8px;
  text-align: center;
  cursor: pointer;
  transition: all 0.15s ease;
  background: var(--card);
  min-height: 64px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.preset:hover {
  border-color: var(--primary-border);
  box-shadow: var(--shadow-hover);
}

.preset.active {
  border-color: var(--primary);
  background: var(--primary-light);
}

.preset-name {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 4px;
}

.preset.active .preset-name {
  color: var(--primary);
}

.preset-size {
  font-size: 12px;
  color: var(--text-secondary);
}

.custom-panel {
  display: none;
  background: var(--bg);
  border-radius: var(--radius-sm);
  padding: 16px;
  margin-top: 12px;
}

.custom-panel.show { display: block; }

.slider-row {
  display: flex;
  align-items: center;
  gap: 12px;
}

.slider-row input[type="range"] {
  flex: 1;
  height: 6px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--border);
  border-radius: 3px;
  outline: none;
}

.slider-row input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  background: var(--primary);
  border-radius: 50%;
  cursor: pointer;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}

.slider-row input[type="range"]::-moz-range-thumb {
  width: 18px;
  height: 18px;
  background: var(--primary);
  border-radius: 50%;
  cursor: pointer;
  border: none;
}

.slider-value {
  min-width: 70px;
  text-align: right;
  font-size: 14px;
  font-weight: 600;
  color: var(--primary);
}

.tip {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  font-size: 13px;
  color: var(--text-secondary);
  margin: 0;
}

.tip-icon {
  flex-shrink: 0;
  font-size: 14px;
  margin-top: 2px;
}

.file-list {
  margin-top: 4px;
}

.empty-state {
  text-align: center;
  color: var(--text-secondary);
  font-size: 14px;
  padding: 24px 0;
}

.file-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px;
  background: var(--bg);
  border-radius: var(--radius-sm);
  margin-bottom: 10px;
}

.file-thumb {
  width: 48px;
  height: 48px;
  border-radius: 8px;
  object-fit: cover;
  background: var(--card);
  flex-shrink: 0;
}

.file-info {
  flex: 1;
  min-width: 0;
}

.file-name {
  font-size: 14px;
  font-weight: 500;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.file-meta {
  font-size: 12px;
  color: var(--text-secondary);
}

.file-status {
  font-size: 14px;
  font-weight: 600;
  flex-shrink: 0;
  min-width: 48px;
  text-align: right;
}

.file-status.ready { color: var(--text-tertiary); }
.file-status.processing { color: var(--primary); }
.file-status.done { color: var(--success); }

.retry-btn {
  color: var(--error);
  cursor: pointer;
  font-size: 13px;
  padding: 2px 8px;
  border: 1px solid var(--error);
  border-radius: 6px;
}

.retry-btn:hover { background: #fef2f2; }

.spinner {
  display: inline-block;
  width: 16px;
  height: 16px;
  border: 2px solid var(--primary-border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }

.actions {
  display: flex;
  gap: 12px;
  margin-top: 20px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
  border: none;
  outline: none;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
}

.btn-primary:hover:not(:disabled) { background: #1d4ed8; }
.btn-primary:disabled { opacity: 0.6; cursor: not-allowed; }

.btn-secondary {
  background: var(--card);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover { background: var(--bg); }

.download-hint {
  margin: 16px 0 0;
  font-size: 13px;
  color: var(--success);
  text-align: center;
}

.download-hint.error { color: var(--error); }

footer {
  text-align: center;
  color: var(--text-tertiary);
  font-size: 13px;
  margin-top: 24px;
  line-height: 1.8;
}

@media (max-width: 640px) {
  body {
    padding: 24px 12px 40px;
  }
  h1 { font-size: 24px; }
  .presets {
    grid-template-columns: repeat(2, 1fr);
  }
  .upload-zone {
    padding: 36px 16px;
  }
  .actions {
    flex-direction: column;
  }
  .btn { width: 100%; }
  .card { padding: 20px 16px; }
}