I checked how you do it: <script src="{{=URL('static','js/*modernizr-1.7.min*.js')}}"></script> <script src="{{=URL('static','js/modernizr.custom.js')}}"></script>
It is better to have a version number: *modernizr-1.7.min.j* * * The browser load the .js file in its cache. If you use always the same name modernizr.*custom*.js, then there is no way for the browser to know there is a new version and there is no way you visitors to know that. The only way the visitors to use the new version is to clear their browser cache. So when downloading from the trunk I always have to modify the layout.html. Please consider this.