Clean up CSS border color styles
Created by: sqs
Previously, we had many ways of setting border colors:
- Sometimes the hex color values would be used directly, and a component would define its own light and dark theme variants. This leads to inconsistent color usage, adds code complexity, and is mistake-prone.
- We had
$color-border
,$color-border-2
,$border-color
,--border-color
, etc.
Now we just have --border-color
and --border-color-2
(dimmer, rarely used). Some components' borders will have slightly different colors after this change if they previously used a non-standard border color.