To add a little to Monique's suggestions, here are a couple of CSS snippets we used for our restyled search.
Large search box with rounded corners:
#lia-body .lia-content .lia-component-quilt-header .lia-component-common-widget-search-bar input.search-input {
height: 80px;
width: 849px;
font-size: 40px;
-webkit-border-radius: 4px;
-moz-border-radius: 4px;
border-radius: 4px;
border-width: 1px;
border-color: #cdcdcd;
}
Rounded corners will degrade nicely to square corners on older browsers.
Restyled search button:
#lia-body .lia-content .lia-component-quilt-header .lia-component-common-widget-search-bar .lia-button {
height: 80px;
width: 100px;
background-color: #ed1556;
border-color: #ed1556;
background-image: url(/html/assets/search.png);
}
You can see the full thing here: http://forums.jawbone.com