Very easy: don't set a size and use em units in your CSS. font-size: 1em; Imho it's also much better to use em units for margins and paddings because this w

Very easy: don't set a size and use em units in your CSS. font-size: 1em; Imho it's also much better to use em units for margins and paddings because this will make everything look like it belongs together, even for users that use a very large font size.