node_modules/@covalent/core/data-table/data-table.component.scss

$backdrop-index: 80;
$checkbox-size: 18px;

:host {
  display: block;
  overflow: hidden;
  .td-data-table-scrollable {
    position: relative;
    overflow: auto;
    height: calc(100% - 56px);
  }
}

.td-data-table-column-resizer {
  &, .td-data-table-column-separator {
    position: absolute;
    height: 100%;
    top: 0;
  }
  .td-data-table-column-separator {
    left: 2px;
  }
  right: 0;
  width: 6px;
  cursor: col-resize;
  &.td-resizing {
    cursor: -webkit-grabbing;
  }
}

table.td-data-table {
  width: auto !important;
  &.mat-selectable tbody > tr.td-data-table-row {
    transition: background-color 0.2s;
  }

  &.mat-selectable .td-data-table-column,
  &.mat-selectable th.td-data-table-column,
  &.mat-selectable td.td-data-table-cell {
    &:first-child > .td-data-table-column-content-wrapper {
      width: 18px;
      min-width: 18px;
      padding: 0 24px;
    }
    &:nth-child(2) > .td-data-table-column-content-wrapper {
      padding-left: 0;
    }
    [dir='rtl'] & {
      &:nth-child(2) > .td-data-table-column-content-wrapper {
        padding-right: 0;
        padding-left: 28px;
      }
    }
  }

  td.mat-checkbox-cell,
  th.mat-checkbox-column {
    min-width: 42px;
    width: 42px;
    font-size: 0 !important;
    mat-pseudo-checkbox {
      width: $checkbox-size;
      height: $checkbox-size;
      ::ng-deep &.mat-pseudo-checkbox-checked::after {
        width: 11px !important;
        height: 4px !important;
      }
    }
    mat-checkbox {
      ::ng-deep .mat-checkbox-inner-container {
        width: $checkbox-size;
        height: $checkbox-size;
        margin: 0;
      }
    }
  }
}