:root{
  --bg:#f5f6fa;
  --card:#fff;
  --accent:#2b6cb0;
  --muted:#666;
}
*{box-sizing:border-box}
body{
  margin:0;
  font-family:Inter, Roboto, Arial, sans-serif;
  background:var(--bg);
  color:#111;
}
header{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  padding:16px;
  background:linear-gradient(90deg, #fff, #f8fbff);
  border-bottom:1px solid #e6e9ef;
}
h1{margin:0;font-size:20px}
.controls{display:flex;align-items:center;gap:8px}
.controls input[type=file]{padding:6px}
main{
  display:grid;
  grid-template-columns: 200px 1fr 320px;
  gap:16px;
  padding:16px;
  height: calc(100vh - 70px);
}
#thumbnailsPanel{
  background:var(--card);
  padding:12px;
  border-radius:8px;
  box-shadow:0 6px 18px rgba(20,30,50,0.06);
  overflow-y: auto;
}
#thumbnailsContainer {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.thumbnail {
  position: relative;
  cursor: pointer;
  border: 2px solid transparent;
  border-radius: 4px;
  overflow: hidden;
  transition: all 0.2s;
}
.thumbnail:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}
.thumbnail.active {
  border-color: var(--accent);
  box-shadow: 0 4px 8px rgba(43, 108, 176, 0.3);
}
.thumbnail canvas {
  width: 100%;
  height: auto;
  display: block;
}
.page-number {
  position: absolute;
  bottom: 4px;
  right: 4px;
  background: rgba(0,0,0,0.7);
  color: white;
  padding: 2px 6px;
  border-radius: 3px;
  font-size: 10px;
}
#viewerWrapper{
  overflow:auto;
  background:linear-gradient(#f8fbff, #fff);
  padding:16px;
  border-radius:8px;
  display: flex;
  justify-content: center;
}
#viewer{
  max-width:900px;
  width: 100%;
}
canvas.page-canvas{
  display:block;
  margin:14px auto;
  border-radius:4px;
  box-shadow:0 4px 12px rgba(10,20,40,0.06);
}
#toolsPanel{
  background:var(--card);
  padding:12px;
  border-radius:8px;
  box-shadow:0 6px 18px rgba(20,30,50,0.06);
  overflow-y: auto;
}
.tool{
  margin-bottom:20px;
  padding-bottom: 16px;
  border-bottom: 1px solid #eaeef5;
}
.tool:last-child {
  border-bottom: none;
}
.tool input[type=text]{
  width:100%;
  padding:8px;
  border:1px solid #e0e6f0;
  border-radius:6px;
  margin-bottom: 8px;
}
.zoom-controls {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
#zoomSlider {
  width: 100%;
}
.quick-zoom {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6px;
  margin-top: 4px;
}
.quick-zoom button {
  padding: 6px 4px;
  font-size: 11px;
  background: #f7fafc;
  color: #4a5568;
  border: 1px solid #e2e8f0;
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.2s;
}
.quick-zoom button:hover {
  background: #edf2f7;
  border-color: #cbd5e0;
}
.quick-zoom button:active {
  background: #e2e8f0;
}
button{
  background:var(--accent);
  color:white;
  padding:8px 10px;
  border-radius:6px;
  border:none;
  cursor:pointer;
  transition: background 0.2s;
}
button:hover {
  background: #2c5282;
}
button[disabled]{
  opacity:0.6;
  cursor:not-allowed;
}
.button-group {
  display: flex;
  gap: 8px;
  margin-bottom: 8px;
}
.button-group button {
  flex: 1;
  font-size: 12px;
  padding: 6px 8px;
}
.hint{
  font-size:12px;
  color:var(--muted);
  margin: 0;
}
.selection{
  position:absolute;
  border:2px dashed #ff5a5f;
  background:rgba(255,90,95,0.08);
  pointer-events:none;
  z-index:9999;
}
#info{
  font-size:13px;
  color:var(--muted);
  line-height: 1.4;
}
@media (max-width:1200px){
  main{
    grid-template-columns: 160px 1fr 280px;
  }
}
@media (max-width:900px){
  main{
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr auto;
    height: auto;
  }
  #thumbnailsPanel {
    max-height: 200px;
  }
  #thumbnailsContainer {
    flex-direction: row;
    overflow-x: auto;
  }
  .thumbnail {
    min-width: 100px;
  }
  .quick-zoom {
    grid-template-columns: 1fr 1fr 1fr 1fr;
  }
}