A DESCRIPTION OF THE PROBLEM :
Underline and wavy underline are important visual styling properties for CodeArea. Underline is often used to denote links, while wavy underline is used to draw attention, such as highlighting errors. These properties are widely used in code editors across popular IDEs.

At the same time, it's important to note that this issue is related to styling these properties via a CSS file using class selectors. The significance of this note lies in the fact that RichParagraph.Builder provides a method addWavyUnderline(int start, int length, Color color). However, when aiming for a complete separation of CSS styles from code (the most optimal and recommended way to use CSS), this method cannot be used, as all styles are contained within the CSS class and applied to text segments via the unified method RichParagraph.Builder addWithStyleNames(String text, String... css).

Therefore, I suggest adding the ability to style underline and wavy underline using styles from a CSS file and the RichParagraph.Builder addWithStyleNames(String text, String... css) method.