Search box input box in menus area

I have a problem with the Search box width when positioned in the Menus area. I am using the Contrast theme as basis, with some little things modified.
The search input box shows up layer wide. I want to keep that input box to a certain width, lets say 15 em. And I want the submit button to go to the right of that input button, instead of underneath as now it does.
I have tried modifying the style.css with the tag:
#search-block-form .form-submit{
float: left;
}

with no result for the submit button.
I have read all these discussions about creating the search-theme-block.tpl.php(http://drupal.org/node/206370) and tried that too. It didn't adjust my input box width and submit button position.
Any suggestions?