Use the tab-size property. You’ll need vendor prefixes currently. Example:
pre
{
-moz-tab-size: 4;
-o-tab-size: 4;
tab-size: 4;
}
See also the article on developer.mozilla.org: tab-size.
.tabstop
{
-moz-tab-size: 4;
-o-tab-size: 4;
tab-size: 4;
}
Unstyled tabs (browser default)
<pre>
one tab
two tabs
three tabs
</pre>
Styled tabs (4em)
<pre class="tabstop">
one tab
two tabs
three tabs
</pre>