global.css inconsistent custom properties for light/dark themes

[tomasohCHOM]

What happened?

/static/global.css defines all the custom properties used across the entire website. However, it can be confusing to distinguish the value of the properties based on whether light or dark theme is on. For example, the properties --acm-dark and --acm-light are actually switched depending on the website's current theme.

To fix this, we could rename these properties (and all the references across the entire codebase) using more general terms for the theme properties, such as --acm-primary, or --acm-contrast, instead of --acm-dark or --acm-light.