Minor changes to fix compatibility with older browsers

[Jazzzny]

This PR provides 2 changes to fix compatibility with older browsers.

1. Older browsers that do not support the prefers-color-scheme media query will fail to load any CSS when the dark/light mode code is enabled.

Additionally, the W3 Specification states that the light theme should be loaded as a fallback if no preference is given.

This can trivially be resolved by removing the prefers-color-scheme: light media query from the light theme, to set it as the default if the browser does not handle the query.

Screen.Recording.2024-10-26.at.1.51.18.PM.mov

This does not impact browsers that support the query, as prefers-color-scheme takes priority over the "base" stylesheet:

2. Older browsers do not support addEventListener on matchMedia, instead add a fallback using addListener.

[Jazzzny]

Appended with a fallback for addEventListener. This makes the editor fully functional on every browser I have tested, back to Safari 5.1.7.