Add heading colors to dark theme
--mdoc-section-title-color: #ddd;
--mdoc-section-h2-color: #ddd;
--mdoc-section-h3-color: #ddd;
+ --mdoc-section-h4-color: #ddd;
+ --mdoc-section-h5-color: #a1afb7;
+ --mdoc-section-h6-color: #a1afb7;
--mdoc-toc-title-color: #a0a1a0;
--mdoc-toc-title-background-color: #272f33;
