Flexbox

Since MediaWiki 1.27, mixins for using flexbox in MediaWiki Less files are available in mediawiki.mixins.less.

These support all browsers that implemented at least one of the specs, including Internet Explorer 10, but still require a fallback for those that don't implement anything (anything totally ancient, Internet Explorer 9 or earlier, etc). Just use some floats or something and don't worry about responsiveness for those.

Mixins available:

Random example usage: