About font color.
The font color is follow from VS Code? Or from this PrintCode project? Thank you.
Syntax coloring comes from CodeMirror https://codemirror.net/ css this extension is using. Now it's also possible to add your own css definitions if there's something you want to change.
Because my code is c/c++,but it printed is not colorful. Only number,comment and string have color. How about add your own css definitions? Thank you.
You're getting something like this https://codemirror.net/2/mode/clike/ . If you want more coloring, please make a PR or feature request to CodeMirror project.
I'm not even getting the C-like of CodeMirror:

why we cannot use the css in vscode? I use custom plugin for c++ highlight, so the problem is same with @pchaigno