Set inner table border in HTML

How do I set the "inner border" - the border between different cells.

By setting style attributes I manage to control the outer border, but the inner border just stays the same gray color and the sa开发者_Go百科me width. What attributes should I tweak to control the inner border?

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For ordinary table markup, here's a short solution that works on all devices/browsers on BrowserStack, except IE 7 and below:

table { border-collapse: collapse; }

td + td,
th + th { border-left: 1px solid; }
tr + tr { border-top: 1px solid; }

For IE 7 support, add this:

tr + tr > td,
tr + tr > th { border-top: 1px solid; }

A test case can be seen here: http://codepen.io/dalgard/pen/wmcdE

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You need to style the <td> element.

Take a look at the W3C website