1、CSS Tables

To specify table borders in CSS, use the border property.

The example below specifies a black border for <table>, <th>, and <td> elements:

table, th, td {
  border: 1px solid black;
}

Collapse Table Borders

The border-collapse property sets whether the table borders should be collapsed into a single border:

table {
  border-collapse: collapse;
}

table, th, td {
  border: 1px solid black;
}

CSS：Tutorial four

原文：https://www.cnblogs.com/Nyan-Workflow-FC/p/10519634.html