.jupyter/custom/custom.css
I'm using migu-1m font by downloading for Windows. For Ubuntu, no font setting required because it's default font is not bad.
custom.css
.CodeMirror pre,
.CodeMirror-dialog,
.CodeMirror-dialog .CodeMirror-search-field,
div.output pre,
div.output_html td,
div.prompt,
div.completions select,
div.container pre,
div.tooltiptext pre,
.terminal-app .terminal
{
font-family: migu-1m;
font-size: 10pt;
}
https://stackoverflow.com/questions/22386359/how-to-change-font-in-ipython-notebook
https://stackoverflow.com/questions/45544741/python-jupyter-change-default-font