Hello there! 
I’m new to Obsidian and I was looking for a way to have a customize line length, but as you know Obsidian only offers the “Readable line length” setting with no possibility to adjust it the way you want.
So, while browsing the forum I came across this topic which deals with this problem: https://forum.obsidian.md/t/a-fix-for-ugly-long-lines-in-fullscreen-v2/1279
Having been opened in 2019, I take the liberty of creating a new one to propose my solution. I am not a developer at all so I think my solution will displease those who are, but it works for me.
I’m using Obsidian 0.14.2 and Kepano’s “Minimal” Obsidian 5.1.9 theme.
Add this to your Obsidian.css:
:root {
--line-width: 50rem !important;
/*Enter any value you like*/
}
- Readable line length must be activated
- It works in Live Preview, Source Mode and Reading
- This solves the problem of the scrollbar attached to the resized block with Frederick_Lost’s code (@BENWF)
I know that the use of !important is not optimal in CSS, but then again I am not a developer.
Some examples to show that it works:
Thanks to @anon41283346 and @rsdimitrov for the inspiration.