Composition mode ala focused Scrivener full screen editing with black bars on either side

TL;DR: Is there a mod, CSS or other way to include black bars on either side (or throughout screen) when using a full screen Focus mode type mod?

I’ve posted this on the reddit as well in case anyone there has suggestions for something that does this already.

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This program is awesome. I didn’t think I’d find anything on par with Scrivener, which I’ve loved for ages, but after the project got past 1.5mil words it got slow to load, and bullets/lists were a nightmare, plus I wanted to be able to refer to bits and pieces on other devices with ease. Obsidian also scratches the old programmer itch, even if I’m not coding for reals I can pretend since the feel can be close enough.

There was one feature I really liked above all else in Scrivener: ‘Composition Mode’. Pressing F11 would activate a kind of super focused mode, but different to any I’m seeing in the mods here. It lets you choose how wide the black bars on either side of the screen were, and how wide and short the main editing area was. You could also choose a font color and background just for this one mode, though I’d survive with just being able to activate black borders on the side. I vaguely recall a small app being able to do that for Windows like a kind of overlay.

This meant that at any time I could have just a small window of absolute focus, surrounded by black, with just faint green text (similar to DOS days). No distractions. Nothing on the periphery. With an extra wide monitor with a general dark desktop background though, switching to focus mode instead means just a lot more light gray on either side, rather than narrowing the view.

I like the default choices for dark backgrounds by Obsidian, or the Thing and Minimalist themes when editing generally, so I’m not trying to switch these off permanently. ‘Ghost Fade’ and ‘Full Screen Focus Mode’ are both great as well.

Thank you for your guidance.

I’m a noob, forgive me for stumbling across the answer after posting my query.

Along with Ghost Fade, this feature is well enough catered for via quickly changing the theme to any of these:

Minimal, with Minimal Theme Settings > Dark Mode Background Contrast > True Black, with Dark Mode Color Scheme either Everforest for the green or Gruvbox for a red just right forlate night low ambient light.

Obsidianite

Terminal

It looks like there are even settings in Minimal Theme Settings for me to play with hotkeys to do this at a moment’s notice.

I love the creators here already.

And the Style Settings plugin which extends the Minimal Theme Settings. Also, not forgetting the Supercharged Links plugin.

Thanks! Just found Style Settings as well, which helped me turn down the font from blistering bright against the true black background contrast. No need for other theme settings after all, but it’s great to be able to switch things with hotkeys.