:root {
  --bg: #eef2f5;
  --panel: #ffffff;
  --ink: #1f2d3d;
  --muted: #627487;
  --line: #d7e0e8;
  --accent: #0b7285;
  --danger: #d9480f;
  --ruler-size: 28px;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background: radial-gradient(circle at 0% 0%, #f9fcff, var(--bg) 45%);
}

.page {
  display: grid;
  grid-template-columns: 360px 1fr;
  min-height: 100vh;
}

.panel {
  border-right: 1px solid var(--line);
  background: var(--panel);
  padding: 20px;
  overflow: auto;
}

h1 {
  margin: 0 0 14px;
  font-size: 22px;
}

.card {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px;
  margin-bottom: 12px;
  background: #fbfdff;
}

h2 {
  margin: 0 0 8px;
  font-size: 16px;
}

.row { display: grid; grid-template-columns: 74px 1fr 60px; align-items: center; gap: 8px; margin-top: 8px; }
.row input[type="range"] { width: 100%; }
.row input[type="number"] { width: 100%; padding: 4px 6px; }
.hint { margin: 8px 0 0; color: var(--muted); font-size: 12px; line-height: 1.5; }
.actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 8px; }

button, input[type="file"] {
  font: inherit;
}

button {
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 8px;
  padding: 7px 12px;
  cursor: pointer;
}
button:hover { border-color: var(--accent); }
button.danger:hover { border-color: var(--danger); color: var(--danger); }

.workspace {
  display: grid;
  grid-template-rows: minmax(420px, 1fr) auto;
  gap: 12px;
  padding: 16px;
}

.canvas-wrap {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 14px;
  overflow: auto;
}

.editor-area {
  position: relative;
  width: fit-content;
  min-width: 300px;
  min-height: 220px;
  margin: 0 auto;
  padding: var(--ruler-size);
  background:
    linear-gradient(45deg, #f0f0f0 25%, transparent 25%),
    linear-gradient(-45deg, #f0f0f0 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, #f0f0f0 75%),
    linear-gradient(-45deg, transparent 75%, #f0f0f0 75%);
  background-size: 16px 16px;
  background-position: 0 0, 0 8px, 8px -8px, -8px 0;
}

#mainCanvas {
  display: block;
  background: transparent;
  box-shadow: 0 0 0 1px #d0d7de inset;
}

.guide-layer {
  position: absolute;
  left: var(--ruler-size);
  top: var(--ruler-size);
  pointer-events: none;
}

.guide {
  position: absolute;
  pointer-events: auto;
  cursor: move;
}
.guide.horizontal { height: 12px; width: 100%; }
.guide.vertical { width: 12px; height: 100%; }
.guide::after {
  content: "";
  position: absolute;
  background: #e03131;
  opacity: 0.95;
}
.guide.horizontal::after {
  left: 0;
  right: 0;
  top: 50%;
  height: 1px;
  transform: translateY(-0.5px);
}
.guide.vertical::after {
  top: 0;
  bottom: 0;
  left: 50%;
  width: 1px;
  transform: translateX(-0.5px);
}

.selection-box {
  position: absolute;
  --box-color: #1c7ed6;
  border: 1px solid var(--box-color);
  background: color-mix(in srgb, var(--box-color) 14%, transparent);
  pointer-events: auto;
  z-index: 2;
}
.selection-edge {
  position: absolute;
  background: transparent;
  z-index: 3;
}
.selection-edge.top,
.selection-edge.bottom {
  left: 8px;
  right: 8px;
  height: 10px;
  cursor: ns-resize;
}
.selection-edge.left,
.selection-edge.right {
  top: 8px;
  bottom: 8px;
  width: 10px;
  cursor: ew-resize;
}
.selection-edge.top { top: 0; }
.selection-edge.bottom { bottom: 0; }
.selection-edge.left { left: 0; }
.selection-edge.right { right: 0; }

.ruler {
  position: absolute;
  background: #f8fbfd;
  border: 1px solid var(--line);
  user-select: none;
}
.ruler.top, .ruler.bottom {
  left: var(--ruler-size);
  height: var(--ruler-size);
}
.ruler.left, .ruler.right {
  top: var(--ruler-size);
  width: var(--ruler-size);
}
.ruler.top { top: 0; }
.ruler.bottom { bottom: 0; }
.ruler.left { left: 0; }
.ruler.right { right: 0; }

.ruler-mark {
  position: absolute;
  background: #8da2b5;
}
.ruler.top .ruler-mark, .ruler.bottom .ruler-mark {
  width: 1px;
  bottom: 0;
}
.ruler.left .ruler-mark, .ruler.right .ruler-mark {
  height: 1px;
  right: 0;
}

.preview-wrap {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px;
}

.preview-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.preview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 10px;
  margin-top: 10px;
}
.preview-item {
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 8px;
}
.preview-item canvas {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 6px;
}
.preview-item p {
  margin: 6px 0 0;
  font-size: 12px;
  color: var(--muted);
}

@media (max-width: 1100px) {
  .page { grid-template-columns: 1fr; }
  .workspace { grid-template-rows: auto auto; }
}