Hi Tone,
Sorry - I missed the time bit of the post!
Assuming you are using a jquery time script (ie jquery.timePicker.js), the style should match the other jquery elements if you are referencing the jquery downloaded from the jquery site having chosen your scheme using the theme roller (or selected a preset scheme).
What results are you getting?
An example of a basic time picker - along with an example of a start/finish time with fixed interval can be found here.
Edit: The jquery library (as far as I know) doesn't include a 'native' time picker, and the li element seems to carry a plain white background regardless of scheme. For the example I linked to above, you would just need to edit the css for the li element to match the scheme selected for the datepicker (in the timepicker.css file).
In the same (stripped-down) example here the list css is:
div.time-picker li {
font-size:12px;
background-image: url(list_bg.jpg);
padding: 1px 1px 1px 6px;
cursor: pointer;
}
The list_bg.jpg is an image file roughly matching my date-picker css.
Not sure if that is what you are after - there isn't really much else to the timepicker select list that jquery can latch on to that wouldn't be referenced in your main custom jquery js.