I didn’t see the custom css explained in detail, just a quick reference of files one may see in the preferences folder. Perhaps I need to keep looking in the guide.
In any case, you can create a custom css file and place it in the Sigil Preferences Folder. Name it: custom_preview_style.css
You can add whatever styling you want (background-color: grey) to that file. You may need to restart Sigil for it to take effect.
|