[ubermammal]

FWIW, it breaks if you use Tab to cycle through the links.

[nthj]

Unfortunately, CSS does not support a "has", "contains", or "parent" selector, which would be required to support this.

    .button:focus + .tip, .tip.open, .tip:has(a:focus)

One line of jQuery should solve:

    $('.tip a').focus(function(){ $('.tip').addClass('open'); }).blur(function(){ $('.tip').removeClass('open'); });