Inconsistent border in Pages menu box tab

[scribu]

Compare to Categories tabs:

[scribu]

We should really try to use the generic .wp-tab-bar and .wp-tab-active classes.

[nacin]

Re-opened #17699 as it was never fixed.

[WraithKenny]

If you drag the Cat box up to change the order, the border might effect Cat instead of Pages.

Bug is sort of difficult to reproduce as it has to do with fractional pixel values and the elements' position on the page (In particular, when the document "flow" places the element's origin at a fractional pixel value). Browser's won't "subpixel render" a border, but instead rounds it to the nearest pixel for screen rendering. The border only shows when rounded in certain cases. (This isn't a browser bug, but intended.)

For example, I have the Publish box followed by Cat and the border shows up. If I change Publish box (not the Category box) css height (via Firebug) from 251.3px (calculated value) to 251px or any other full pixel value, the border bug goes away on Category.

Perhaps using some sort of "vertical rhythm grid" (which is to say, a style standard that enforces full pixel line-heights ​http://24ways.org/2006/compose-to-a-vertical-rhythm ) would fix this bug, and make the admin that much nicer.

Anyway, the root problem is that the ul css height is calculated to be 16.2px combined with a prior element of a fractional pixel height causes the border to be "rounded up" on display.