Stop wasting your time, use CSSFX
The platform is really great. There is also some good tooling (Scene Builder) provided by Oracle or by the community Scenic View, ControlFX, E(fx)clipse, ...
Seeing that it was sometimes painfull to adapt and adjust CSS during JavaFX development, I decided to also provide my contribution.
That's how CSSFX was born at http://www.fxmisc.org/cssfx/.
CSSFX allows CSS changes to be applied directly in your running application.You only have to launch your JavaFX application, modify the CSS sources in your prefered IDE so see direclty the effects of your modification.
Want to see it in action?
Do not hesitate to give me some feedback on the usage you will do of it.
EDIT: version 1.0.0 is now published, see announce
CSSFX is currently on his way to maven central but is already accessible on sonatype OSS snapshots (https://oss.sonatype.org/content/repositories/snapshots) via:
<dependency>
<groupId>org.fxmisc.cssfx</groupId>
<artifactId>cssfx</artifactId>
<version>0.0.1-rc01-SNAPSHOT</version>
</dependency>
If you want to reach-it on sonatype oss then you'd probably have to declare the oss snapshot repository
<repositories>
<repository>
<id>sonatype-oss</id>
<name>sonatype-oss</name>
<url>https://oss.sonatype.org/content/repositories/snapshots/</url>
<releases>
<enabled>false</enabled>
<updatePolicy>never</updatePolicy>
</releases>
<snapshots>
<enabled>true</enabled>
<updatePolicy>daily</updatePolicy>
</snapshots>
</repository>
</repositories>