* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  background: #f2f3f5;
  color: #1f2329;
}
header { padding: 24px 32px 8px; }
header h1 { margin: 0 0 4px; font-size: 22px; }
header p { margin: 0; color: #646a73; font-size: 13px; }
main { padding: 16px 32px 40px; }
#drop-zone {
  border: 2px dashed #c4c9d1;
  border-radius: 12px;
  background: #fff;
  text-align: center;
  padding: 64px 16px;
  cursor: pointer;
}
#drop-zone.over { border-color: #3370ff; background: #f0f5ff; }
#drop-zone .big { font-size: 18px; margin: 0 0 8px; }
#drop-zone .hint { color: #8f959e; margin: 0; font-size: 13px; }
#workspace .toolbar {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  background: #fff;
  border: 1px solid #e4e6ea;
  border-radius: 10px;
  padding: 10px 16px;
  margin-bottom: 12px;
  font-size: 13px;
}
.toolbar label { display: flex; align-items: center; gap: 6px; }
.toolbar select, .toolbar input {
  padding: 4px 8px;
  border: 1px solid #d5d8dd;
  border-radius: 6px;
  font-size: 13px;
}
.toolbar input[type="number"] { width: 64px; }
#export-btn {
  padding: 7px 18px;
  border: none;
  border-radius: 8px;
  background: #3370ff;
  color: #fff;
  font-size: 14px;
  cursor: pointer;
}
#export-btn:disabled { background: #9ab4ff; cursor: wait; }
#dims-info { color: #646a73; }
#preview {
  overflow: auto;
  background:
    linear-gradient(45deg, #eee 25%, transparent 25%, transparent 75%, #eee 75%),
    linear-gradient(45deg, #eee 25%, #fff 25%, #fff 75%, #eee 75%);
  background-size: 16px 16px;
  background-position: 0 0, 8px 8px;
  border: 1px solid #e4e6ea;
  border-radius: 10px;
  padding: 16px;
}
#toast {
  position: fixed;
  left: 50%;
  bottom: 32px;
  transform: translateX(-50%) translateY(20px);
  background: #1f2329;
  color: #fff;
  padding: 10px 20px;
  border-radius: 8px;
  font-size: 14px;
  opacity: 0;
  pointer-events: none;
  transition: all 0.25s;
  max-width: 80vw;
}
#toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
#toast.err { background: #d83931; }
#cell-edit label { display: inline-flex; align-items: center; gap: 4px; }
#cell-edit b { font-weight: 600; }
#preview td.hs-selected { outline: 2px solid #3370ff; outline-offset: -2px; }