How to remove the apparently un-removable input type="search" border in Chrome
Apparently Webkit has a custom style for search input fields. You can get rid of it directly then apply your own borders. I removed it here and gave it a red border.
input{ -webkit-appearance: none; border: 1px solid red;}
I've only looked at this in Chrome.
You should try
-webkit-appearance: none;
Also see http://37signals.com/svn/posts/2609-customizing-web-forms-with-css3-and-webkit