antd-mobile/es/components/tree-select/tree-select.css

<div align="center">

.adm-tree-select,
.adm-tree-select-multiple {
  display: flex;
  height: 100%;
  font-size: var(--adm-font-size-main);
  background-color: var(--adm-color-white);
}
.adm-tree-select-column,
.adm-tree-select-multiple-column {
  overflow-y: auto;
  transform: translateZ(0);
  -webkit-transform: translateZ(0);
}
.adm-tree-select-column:first-child,
.adm-tree-select-multiple-column:first-child {
  background-color: var(--adm-color-box);
}
.adm-tree-select-column:nth-child(2),
.adm-tree-select-multiple-column:nth-child(2) {
  background-color: var(--adm-color-box);
}
.adm-tree-select-item,
.adm-tree-select-multiple-item {
  display: flex;
  align-items: center;
  min-height: 50px;
  box-sizing: border-box;
  padding: 6px 12px;
  position: relative;
}
.adm-tree-select-item-active {
  color: var(--adm-color-primary);
  font-weight: bold;
  background-color: white;
}
.adm-tree-select-multiple-item-expand {
  color: var(--adm-color-primary);
  font-weight: bold;
  background-color: white;
}
.adm-tree-select-multiple-item-checkbox {
  margin-right: 8px;
}
.adm-tree-select-multiple-dot {
  position: absolute;
  top: 50%;
  margin-top: -3px;
  right: 8px;
  width: 6px;
  height: 6px;
  background: var(--adm-color-primary);
  border-radius: 3px;
}