ASP.Net is weird. A Button element is actually a html input element; an input element breaks the css for button group in an input group *(the find input and box are an example [bootstraps](http://getbootstrap.com/components/#input-groups-buttons) 'input group')*
`<button id="searchButton" class="btn btn-default" runat="server" onserverclick="searchButton_Click">Find</button>` Should probably work as a replacement, to get the css working again.