Milo added tabs for timeline using the jquery ui tab's library.  However, this implementation has some issues:

* Content is hidden prior to jquery being loaded, and the reflow cost may be significant.  On large builds, there may be a 100-200ms flicker.
* Does not support responsive layout natively w/o javascript (ie using css media queries)

It'd be better to make the tabs implementation using native HTML/CSS, for performance reasons.