border-spacing

The border-spacing value is also used along the outside edge of the table, where the distance between the table's border and the cells in the first/last column or row is the sum of the relevant (horizontal or vertical) border-spacing and the relevant (top, right, bottom, or left) padding on the table.

/* <length> */
border-spacing: 2px;

/* horizontal <length> | vertical <length> */
border-spacing: 1cm 2em;

/* Global values */
border-spacing: inherit;
border-spacing: initial;
border-spacing: revert;
border-spacing: revert-layer;
border-spacing: unset;

The border-spacing property may be specified as either one or two values.

• When one <length> value is specified, it defines both the horizontal and vertical spacings between cells.
• When two <length> values are specified, the first value defines the horizontal spacing between cells (i.e., the space between cells in adjacent columns), and the second value defines the vertical spacing between cells (i.e., the space between cells in adjacent rows).

<length>

The size of the spacing as a fixed value.

border-spacing = 
  <length>{1,2}  

This example applies a spacing of .5em vertically and 1em horizontally between a table's cells. Note how, along its outside edges, the table's padding values are added to its border-spacing values.

HTML

<table>
  <tr>
    <td>1</td><td>2</td><td>3</td>
  </tr>
  <tr>
    <td>4</td><td>5</td><td>6</td>
  </tr>
  <tr>
    <td>7</td><td>8</td><td>9</td>
  </tr>
</table>

CSS

table {
  border-spacing: 1em .5em;
  padding: 0 2em 1em 0;
  border: 1px solid orange;
}

td {
  width: 1.5em;
  height: 1.5em;
  background: #d2d2d2;
  text-align: center;
  vertical-align: middle;
}

Result

• border-collapse, border-style
• The border-spacing property alters the appearance of the <table> HTML element.