Styling form controls with CSS, revisited
CSS 2.1 does not define which properties apply to form controls and frames, or how CSS can be used to style them. User agents may apply CSS properties to these elements. Authors are recommended to treat such support as experimental. A future level of CSS may specify this further.
In other words, don’t blame the browsers for the inconsistent results.
Here are a few of my favourite weird effects that applying CSS to form controls can have:

