Never noticed this before: the auto-complete appears under the slider handles (Chrome 10). Shall test for other browsers in a bit...
edit:
Chrome 12 Canary: same as Chrome 10
IE9 beta: Handles on top, buttons look fine, though no text shadow. "<>" are poorly anti-aliased.
IE9 beta in compatibility mode: auto-complete on top (?), but buttons (aside from href) are full-width. "<>" are poorly anti-aliased.
FF4 rc: Handles on top. "<>" are poorly anti-aliased.
FF3.6.15: Handles on top. "<>" are poorly anti-aliased.