table边框

table {

  width: 50vw;

  margin: 50px;

  //border

  border-top: 1px solid gray;

  border-left: 1px solid gray;

  border-collapse: collapse;

  th,

  td {

    text-align: center;

    //border

    border-bottom: 1px solid gray;

    border-right: 1px solid gray;

  }

}