feat: generate css from theme

src/typst.rs

@@ -30,6 +30,12 @@ impl TypstContext {
                 Value::Func(crate::syntax::highlight_func()),
             );
         }
+        if config.themes_root.is_some() {
+            inputs.insert(
+                "theme_css".into(),
+                Value::Func(crate::themes::theme_css_func()),
+            );
+        }
         let library = Library::builder()
             .with_inputs(inputs)
             .with_features([typst::Feature::Html].into_iter().collect())