drupal/core/themes/seven/css/components/tables.css

/**
 * Tables.
 */
table {
  width: 100%;
  margin: 0 0 10px;
  font-size: 0.923em;
}
caption {
  text-align: left; /* LTR */
}
[dir="rtl"] caption {
  text-align: right;
}
th {
  text-align: left; /* LTR */
  padding: 10px 12px;
}
[dir="rtl"] th {
  text-align: right;
}
thead th {
  background: #f5f5f2;
  border: solid #bfbfba;
  border-width: 1px 0;
  color: #333;
  text-transform: uppercase;
}
tr {
  border-bottom: 1px solid #e6e4df;
  padding: 0.1em 0.6em;
}
thead > tr {
  border-bottom: 1px solid #000;
}
tbody tr:hover {
  background: #f7fcff;
}
td,
th {
  vertical-align: middle;
}
td {
  padding: 10px 12px;
  text-align: left; /* LTR */
}
[dir="rtl"] td {
  text-align: right;
}
th > a {
  position: relative;
  display: block;
}

/* 1. Must match negative bottom padding of the parent <th> */
th > a:after {
  content: '';
  display: block;
  position: absolute;
  top: 0;
  bottom: -10px; /* 1. */
  left: 0;
  right: 0;
  border-bottom: 2px solid transparent;
  -webkit-transition: all 0.1s;
  transition: all 0.1s;
}
th.active > a {
  color: #004875;
}
th.active img {
  position: absolute;
  right: 0; /* LTR */
  top: 50%;
}
[dir="rtl"] th.active img {
  right: auto;
  left: 0;
}
th.active > a:after {
  border-bottom-color: #004875;
}
th > a:focus,
th > a:hover,
th.active > a:focus,
th.active > a:hover {
  color: #008ee6;
  text-decoration: none;
}
th > a:focus:after,
th > a:hover:after,
th.active > a:focus:after,
th.active > a:hover:after {
  border-bottom-color: #008ee6;
}
td .item-list ul {
  margin: 0;
}
td.active {
  background: none;
}

/* Force browsers to calculate the width of a 'select all' TH element. */
th.select-all {
  width: 1px;
}

/**
 * Captions.
 */
.caption {
  margin-bottom: 1.2em;
}

/**
 * Status report table.
 */
table.system-status-report tr {
  border-top: 1px solid #ccc;
  border-left: 1px solid #bebfb9;
  border-right: 1px solid #bebfb9;
  border-bottom: inherit;
}
table.system-status-report tr:first-child {
  border-top: 1px solid #bebfb9;
}
table.system-status-report tr:last-child {
  border-bottom: 1px solid #bebfb9;
}

table.system-status-report tr.ok {
  color: #255b1e;
  background-color: #e5ffe2;
}
table.system-status-report tr.warning {
  color: #840;
  background-color: #fffce5;
}
table.system-status-report tr.error {
  color: #8c2e0b;
  background-color: #fef5f1;
}

/**
 * Responsive tables.
 */
@media screen and (max-width: 37.5em) { /* 600px */
  th.priority-low,
  td.priority-low,
  th.priority-medium,
  td.priority-medium {
    display: none;
  }
}
@media screen and (max-width: 60em) { /* 920px */
  th.priority-low,
  td.priority-low {
    display: none;
  }
}