Asp.net webpage has a lot of blank space at bottom

My asp.net webpage has a ton of white space at the bottom of a div within a content page, and I have no idea where its coming from. There are NOT a ton of <br /> 's or &nbsp's in the source view. How can I find out where the space is coming from and correct?

Could this element be taking up space???

   <ul style="display: none; visibility: hidden; z-index: 10000; overflow-x: hidden; overflow-y: auto; width: 246px; position: absolute; height: 320px;" class="ajax__combobox_itemlist" id="ctl00_ctl00_PageContent_PageContent_cboTurnOver_OptionList"><li>&nbsp;</li><li>Aaron Ament - 034  </li><li>Aaron Stack - 235开发者_StackOverflow  </li><li>Accounting  - OA   </li><li>Adam Kauth - 289  </li><li>Admin  - 481  </li><li>Aimee Tatge - 149  </li><!--Over 100 entries removed for security and brevity--><li>Zeddie Roshelle - 346  </li></ul>

Using Firebug inspect the whitespace to see which element it is in your html. Or in Chrome right click on it and select inspect element. The relevant source will be highlighted for you.

My guess is that this a style related item. The "Developer Toolbar" for FireFox is a great plugin for this type of thing as it allows you to inspect the document and see what is taking up the space.

Look through the CSS style sheet for a "min-height" rule being applied.

Make sure you don't have any whitespace in your viewpage at the bottom. If you also see nothing in the source - check your css, as you could have something funky going on there.

Check your page with internet explorer developer tool or firefox firebug and look for

and tag margins with firebug you can manupulate the html code to see what happen on the fly Firebug download

also you can send me your online version I should have a look at it for you