Add support for background-clip & prepare for multilayered backgrounds!

Add shorthand property parsing.

Fix transformation matrix (should be fixed upstream, but that'd be breaking).

Fix colour output, add OpenGL cleanup.

Improve debuggability, correct rect shrinking.

Add test script!

Implement background-colour rendering!

Draft background-colour shader.

Integrate backgrounds parsing.

Improve code cleanliness.

Handle initial colour values.

Parse background-colour CSS property.

Integrate colour parsing & add accent-colour support.

accent-colour takes no effort & helps (custom) form controls clash less with webpages.

Add support for transparent, currentcolor, & hsl() colours!

Parse CSS colour hexcodes & keywords.

Start parsing CSS colours!