We have seen that SLD has very powerful styling capabilities, although due to XML's verbose nature, SLD documents can easily become unmanageable with the style's complexity. XML is great for computers; they can easily parse and serialize documents in this format. However, they are inconvenient for humans. There is another styling language created for defining styles in a more concise manner--CSS (Cascading Style Sheet). CSS fits human logic better; we just need to understand its cascading behavior. Cascading, in this sense, can be understood with this rule--every matching definition gets applied, but on collision, the most specific definition wins. Let's look at an example. With the following snippet, we can style our GeoNames layer:
* {
mark-size: 6;
}
[featurecode LIKE 'PPLA%'] {
mark: symbol('circle');
}
[featurecode LIKE 'PPLA%'] [population > 100000] {
mark-size: 8;
}The least specific rule is the * wildcard, which selects...