$ cat ~/.config/joplin-desktop/userchrome.css
/* For styling the entire Joplin app (except the rendered Markdown, which is defined in `userstyle.css`) */
/* Notebook Font Size */
span.title, span.tag-label {
font-size: 16px;
}
/* SubNoteBook Font Size */
div.note-list-item > .content > .title > span {
font-size: 16px; font-family: "Times New Roman"; color: black;
}
/* */
.codeMirrorEditor .CodeMirror * {
font-family: "your font name", monospace !important;
}
/* NoteBooks - White Background */
.sidebar {
background-color: purple! important;
}
/* Black Font Color for NoteBooks */
span.title, span tag-label {
color: white! important;
}
https://github.com/alxnbl/onenote-md-exporter https://discourse.joplinapp.org/