Bootstrap/less/mixins/table-row.less

// Tables

.table-row-variant(@state; @background) {
  // Exact selectors below required to override `.table-striped` and prevent
  // inheritance to nested tables.
  .table > thead > tr,
  .table > tbody > tr,
  .table > tfoot > tr {
    > td.@{state},
    > th.@{state},
    &.@{state} > td,
    &.@{state} > th {
      background-color: @background;
    }
  }

  // Hover states for `.table-hover`
  // Note: this is not available for cells or rows within `thead` or `tfoot`.
  .table-hover > tbody > tr {
    > td.@{state}:hover,
    > th.@{state}:hover,
    &.@{state}:hover > td,
    &:hover > .@{state},
    &.@{state}:hover > th {
      background-color: darken(@background, 5%);
    }
  }
}