Suggestion: instructions on installing for Firefox with userContent.css

[AlanDeSmet]

This is how I got the style working in my copy of Firefox 79.0:

Find your OneTab URL

1. Open your OneTab tab; you need the URL which looks something like moz-extension://72c7e844-0d86-4359-b35e-ddf42525461b/onetab.html (The long string of meaningless numbers and letters will almost certainly be different for you!)

Create userContent.css

1. Find your profile directory (check about:support for "Profile Directory")
2. In your profile directory, create a subdirectory chrome if one doesn't already exist
3. In the new chrome directory, create an empty userContent.css if one doesn't already exist
4. Paste the contents of OneTab-Night-Mode onetab.css into the userContent.css
5. Wrap the code you pasted in this to ensure the modifications are only applied to OneTab:

@-moz-document url("moz-extension://72c7e844-0d86-4359-b35e-ddf42525461b/onetab.html") {
/* Contents of onetab.css go here */
}

6. Change the moz-extension://72c7e844-0d86-4359-b35e-ddf42525461b/onetab.html to the OneTab URL found in the first step

Enable legacy user profile customizations:

1. Go to about:config
2. search for toolkit.legacyUserProfileCustomizations.stylesheets
3. If it doesn't say true, click ⇌ to toggle it from false to true

Thanks for creating this style!