By default, CSS files are cached and their imports are merged into a single CSS file at the server side. This reduces the number of HTTP requests from the browser to the server.

The optimization code is quite simple as all the CSS files are parsed at the server startup time and all the @import and url(...) references are rewritten to support a single flat file. The result is stored in a cache directly used from the ResourceRequestFilter.

Although the optimization is useful for production environments, it may be easier to deactivate this optimization while debugging stylesheets. To do so, set the java system property exo.product.developing to true.

For example, the property can be passed as a JVM parameter with the -D option when running GateIn.

sh $JBOSS_HOME/bin/run.sh -Dexo.product.developing=true