In this chapter, you learned a lot about SLD and how to use its elements to produce graphical effects on your maps. While SLD is a powerful tool and enables you to create a complex and pretty rendering of data, it is also famous for being quite hard to write and understand for humans.
Cascading Style Sheets (CSS) (http://en.wikipedia.org/wiki/CSS) is a convenient and easier replacement alternative to long SLD documents. When using CSS, you must be aware that this is GeoServer specific.
While SLD is a standard approach that can be reused with other WMS implementations or a desktop application such as QGIS, CSS is a GeoServer-specific module. For instance, you can't use the CSS syntax with MapServer, but you can, of course, reuse the styles on another GeoServer WMS server, assuming that layers with similar details are published on them.
If you followed the instructions at the start of this chapter, you already installed the CSS module; so, now we are ready to duplicate the thematic...