Ordering the Link States
Spend any time at all writing above-beginner CSS, and you’re going to come across the “link-visited-hover-active” (LVHA) rule. This holds that the four link states should always be listed in that order, like so:
a:link {color: blue;}
a:visited {color: purple;}
a:hover {color: red;}
a:active {color: yellow;}
Masters of the dark arts of specificity know why this rule exists and how it does or doesn’t apply, but if you’re still a padawan in these matters (or just rusty), you can get a quick refresher from this old chestnut of mine.
Now, it’s the case that this will become less of an issue over time becuase IE7 supports (and one presumes future versions of IE will continue to support) chained pseudo-classes, like a:link:hover {color: red;}. Once you start chaining those you transcend a lot of the specificity-ordering concerns that drive the LVHA rule. However, we’re not there yet.
Which brings me to the point of all this: the fifth possible link state, :focus. Assuming we’re going to avoid chaining pseudo-classes for a while yet, but that we want to introduce link-focus styles, where should it fit in the ordering? For the purposes of this discussion, assume the following:
a:focus {color: orange;}
a:link {color: blue;}
a:visited {color: purple;}
a:hover {color: red;}
a:active {color: yellow;}
We need to move the a:focus rule so it has a visible effect. But where? Should it come before a:hover, after a:hover, or after a:active? In other words, which states’ styles should the focus style overwrite?
I’d like to hear your thoughts on the matter, and especially the rationale driving your answer. Accessibility experts are particularly welcome to weigh in, but it’s anyone’s game here.
(Postscript: I know that many problems can be avoided by picking a different styling effect for the focus style, like a border or outline, or boldfacing or italicizing the text of a focused link. Still, some people will want to handle everything through color, regardless of the problems this can cause for the colorblind or images-as-links, and I’d like to address that specific situation. Thanks.)