table滚动条

/*设置 tbody高度大于300px时 出现滚动条*/
table tbody {
  display: block;
  max-height: 300px;
  overflow-y: auto;
}
table thead tr {
  display: table;
  width: 100%;
  table-layout: fixed;
}
table tbody tr {
  display: table;
  width: 100%;
  table-layout: fixed;
}