Modify default markdown styles in JupyterLab


I’m wondering if there’s a way for me to globally modify the default styles that are rendered in markdown cells. For example the default h1 (#) renders a black font. I would like to be able to change it so that any notebook I create uses a gray font when I use the markdown for h1.

I know I can do this with span tags but that get s pretty tedious. Is there a CSS file or other place I can modify the styles that get rendered for markdown tags?

Thanks in advance for any help.