Merge: Firefox Progress Bar Overlap Fix and In-Page “Pause on This Site” Button

[Marrrrrrrrry]

I'm merging two features into the main branch:

A fix for the Firefox browser where the loading progress bar overlaps and obscures main UI elements.
A new "Pause on this site" button on the playback page (e.g., twitter.com), allowing users to temporarily disable the extension directly from the webpage—without needing to navigate to the settings page, toggle the option, and refresh.

[polywock]

Hello! Thank you for the PR! I like the idea, but will probably go about implementing in a slightly different way.

1. While on a website like Github, the user should be able to click the 3 dots menu and disable Global Speed on the current site.
2. It should be reversible in the same way.

[Marrrrrrrrry]

Okay, I don't mind you making changes to my proposal as long as the core functionality remains the same. It's just that I specifically found an SVG icon with the same style as the original, but it might not be needed now, haha. On another note, I fixed the issue where the progress bar was overlapping the main element. I noticed Firefox's progress bar is unusually thick—you can probably reproduce this—so I fixed it.

[polywock]

@Marrrrrrrrry Can you update your pull request to be just this for now.

scrollbar-width: thin;
overflow-x: hidden;

[Marrrrrrrrry]

Okay, so you mean I should only submit the modifications for the file src/popup/popup.css? Actually, you can directly remove the unnecessary parts when merging my code; I agree to this approach.