Initial Proton support

Add support for Proton.

Tested with Default, Dark, and Light theme of Windows and MacOS Big Sur.
Both OS are on dark theme.

Tested container tabs (no highlight) and tabs overflow scrollbox.

Added clearer README on what is regularly tested, and support situation.

Last Photon Support

This release marks the last release where Photon (Firefox 88 and below) is supported.

Firefox 71 fix.

Fix the first tab being cut off in FF 71

v0.8

Various Fixes

v0.7

• Fixed background tab hover.

v0.6

Some fixes

1. Fix Windows background color. This is a new bug I discovered after refreshing my Firefox Profile.
2. Small fix to tab curve so it looks smoother.

v0.5

Changes:

1. Circle icon on hovering over close tab button.
2. Remove tab burst animation when page is loaded.
3. Small clipping bugfix.

Left padding for tabs.

#45

Hovering Tabs should feel better now.

Went back to FF56 to see how did they handle the border between tabs properly on hover, turns out the solution is pretty simple.

v0.3.3

• Fixed Windows 7 styling on light theme.