How to get a lager page width in both editing mode and preview mode?

[GreenChocho]

Thanks for the guide.
I tried applying the code, the scrollbar placement is a bit annoying though.
In the same thread, there are another version of the code which keep the scrollbar at the default place:

A fix for ugly long lines in fullscreen v2

While selecting the whole page there was a glitch, added ‘selected’ div as well. .CodeMirror-lines, .CodeMirror-selected, .markdown-preview-section { max-width: 700px; margin: auto; }