:root {
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --danger: #ef4444;
  --border: #e2e8f0;
  --radius: 8px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  padding: 24px;
}

.app {
  max-width: 900px;
  margin: 0 auto;
}

header {
  margin-bottom: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

h1 {
  font-size: 1.5rem;
  font-weight: 700;
}

.tabs {
  display: flex;
  gap: 8px;
}

.tab-btn {
  background: transparent;
  border: 1px solid var(--border);
  padding: 8px 16px;
  border-radius: var(--radius);
  cursor: pointer;
  font-weight: 500;
}

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

.tab-content {
  display: none;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
}

.tab-content.active {
  display: block;
}

.dropzone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 40px;
  text-align: center;
  color: var(--muted);
  cursor: pointer;
  margin-bottom: 20px;
  transition: border-color 0.2s;
}

.dropzone.dragover {
  border-color: var(--primary);
  background: #eff6ff;
}

.browse-link {
  color: var(--primary);
  cursor: pointer;
  text-decoration: underline;
}

.action-btn {
  background: var(--primary);
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: var(--radius);
  cursor: pointer;
  font-weight: 600;
  margin-top: 16px;
}

.action-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.action-btn:not(:disabled):hover {
  background: var(--primary-hover);
}

.file-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 16px;
}

.file-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: grab;
}

.file-item.dragging {
  opacity: 0.4;
}

.file-item button {
  background: transparent;
  border: none;
  color: var(--danger);
  cursor: pointer;
}

.file-info {
  margin-bottom: 16px;
  font-size: 0.95rem;
  font-weight: 500;
}

.radio-group {
  display: flex;
  gap: 16px;
  margin-bottom: 16px;
}

.input-row {
  margin-bottom: 16px;
}

.input-row label {
  display: block;
  font-size: 0.9rem;
  margin-bottom: 4px;
  color: var(--muted);
}

.input-row input {
  width: 100%;
  max-width: 320px;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.hidden {
  display: none !important;
}

.organize-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.pages-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 16px;
}

.page-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 8px;
  display: flex;
  flex-direction: column;
  align-items: center;
  cursor: grab;
  position: relative;
}

.page-card.dragging {
  opacity: 0.3;
}

.page-card canvas {
  max-width: 100%;
  height: auto;
  border: 1px solid var(--border);
  background: #fff;
  border-radius: 4px;
  transition: transform 0.2s ease;
}

.page-card-footer {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 8px;
  font-size: 0.8rem;
  color: var(--muted);
}

.page-card-actions {
  display: flex;
  gap: 4px;
}

.page-card-actions button {
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 2px 6px;
  cursor: pointer;
  font-size: 0.75rem;
}

.page-card-actions button:hover {
  background: #e2e8f0;
}

.page-card-actions button.btn-del:hover {
  background: var(--danger);
  color: white;
  border-color: var(--danger);
}

/* Multi-PDF Organize */
.organize-workspace {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.doc-group {
  background: #f1f5f9;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px;
  transition: box-shadow 0.2s;
}

.doc-group.dragging {
  opacity: 0.4;
}

.doc-group.drag-target {
  border: 2px dashed var(--primary);
}

.doc-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.doc-drag-handle {
  cursor: grab;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
  user-select: none;
}

.doc-remove-btn {
  background: transparent;
  border: none;
  color: var(--danger);
  cursor: pointer;
  font-size: 1.1rem;
}

/* Convert & Compress UI */
.convert-nav {
  display: flex;
  gap: 8px;
  margin-bottom: 20px;
}

.subtab-btn {
  background: #f1f5f9;
  border: 1px solid var(--border);
  padding: 6px 14px;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
}

.subtab-btn.active {
  background: var(--text);
  color: white;
  border-color: var(--text);
}

.subtab-content {
  display: none;
}

.subtab-content.active {
  display: block;
}

.convert-options {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-top: 12px;
}

.convert-options select {
  padding: 6px 10px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  margin-left: 6px;
}

.result-box {
  margin-top: 16px;
  padding: 14px;
  background: #ecfdf5;
  border: 1px solid #a7f3d0;
  border-radius: var(--radius);
  color: #065f46;
  font-size: 0.95rem;
}

.image-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
  gap: 12px;
  margin-bottom: 16px;
}

.img-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 6px;
  display: flex;
  flex-direction: column;
  align-items: center;
  cursor: grab;
  position: relative;
}

.img-item.dragging {
  opacity: 0.3;
}

.img-item img {
  width: 100%;
  height: 100px;
  object-fit: cover;
  border-radius: 4px;
}

.img-item-footer {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 6px;
  font-size: 0.75rem;
  color: var(--muted);
}

.img-item-footer button {
  background: transparent;
  border: none;
  color: var(--danger);
  cursor: pointer;
}