tab-size

The tab-size property is used to determine the width of the tab character (U+0009) displayed on the page. The width can be set either by explicitly setting a length value for the width or by specifying the number of spaces displayed in place of a tab character.

The value of a tab-size property can be either a <length> value or an <integer>. Integers represent the number of space characters (U+0020) that make up the width of the tab character. Negative values are not allowed. Initially the tab size is set to 8 space characters by default.

Trivia & Notes

Usually, sequences of white spaces are collapsed into one (details in the white-space entry). When tabs are typed in the source of a page, a tab (U+0009) is converted to a sequence of spaces (U+0020) by the white space processing rules, and hence, it is collapsed and rendered as a regular space on the page. The only case when a tab is rendered as a tab on the page is when the pre formatting rule is applied to the content, whether by including the content in a <pre> tag, or by setting the value of the white-space property to pre or pre-wrap. So it would only make sense to use the tab-size property in case we’re preserving the white spaces.

Because of low browser support, you may want to use a polyfill to set the tab size.