We saw earlier that JavaFX advocates the use of CSS (Cascading Style Sheets) to style the controls. While this is consistent with the web way of styling, it can be improved upon by using the type-safe CSS option provided by Tornado FX. In this way, the styles are expressed in pure Kotlin code instead of CSS.
You may notice that this is nothing but a Domain Specific Language (DSL), which is possible in Kotlin because of its expressiveness.