Load extra themes even with theme=css

Closes #1775

Author: Keats

components/config/src/config/markup.rs

@@ -108,14 +108,14 @@ impl Markdown {
             self.extra_syntax_set = Some(extra_syntax_set);
         }
 
-        if self.highlight_theme == "css" {
-            return Ok(());
-        }
-
         if let Some(extra_theme_set) = loaded_extra_highlight_themes {
             self.extra_theme_set = Arc::new(Some(extra_theme_set));
         }
 
+        if self.highlight_theme == "css" {
+            return Ok(());
+        }
+
         // Validate that the chosen highlight_theme exists in the loaded highlight theme sets
         if !THEME_SET.themes.contains_key(&self.highlight_theme) {
             if let Some(extra) = &*self.extra_theme_set {