Readme example vs. setting up line width

[b1uegh0st]

Hi,

Thanks for the great plug-in. I found the example in your readme about the line-width, was looking for something like that. However, I am not seeing it working (maybe coz I use a theme?).

Need

• If the readme is wrong, hope there can be a fix.
• Else, if it is right, can you show some pointers on how to write a setting to adjust the max-width (possibly a different setting) as in the details I added under here?

I know it is a bit more than an Issue request, but because this was in the Readme so I feel somewhat justified to post this issue. Really want to use your plugin as it solves my exact pain point, just that I don't know how to make it to work in my usecase.

Thanks,
NA

Details
To be exact:

/* @settings
name: Your Section Name Here
id: a-unique-id
settings:
- 
id: line-width
title: Line width
description: The maximum line width in rem units
type: variable-number
default: 42
format: rem
*/

My other solution, a CSS snippets: (work in all theme, with the Readable line settings on).

.markdown-preview-view.is-readable-line-width .markdown-preview-sizer, .markdown-source-view.is-readable-line-width .CodeMirror 
{ max-width:42rem; }