I love markdown, and have even done away with word processing altogether. But sometimes I need HTML to help me out where markdown cannot provide.
Obsidian supports certain inline HTML elements (e.g. <!--PB:-->) but, I would like to expand it.
E.g. I use <span style="color:darkviolet">some text</span>, or <p style="color:white;background-color:tomato">text</p> regularly - “darkviolet” and “tomato” are examples.