I recently discovered mermaid.js which is great to design graphs and Gantts. I'm using the live editor (https://mermaid-js.github.io/mermaid-live-editor/) and it's quite easy. But how can I simply change the text font and its size, colors of the tasks in the editor ? I've read that it's possible to do this changing css attributes, but that's not clear for me, I would need some more explanations. Many thanks