Cherry-pick of 2ced31e81d adapted to Forgejo releases UI.
Percentage-based `border-radius` [creates undesirable
ellipse](https://jsfiddle.net/silverwind/j9ko5wnt/4/) on non-square
content. Instead, use pixel value and use same wording `full` like
tailwind does, but increast to 99999px over their 9999px.
(cherry picked from commit 2ced31e81dd9e45659660c1abff529d0192fd8ed)