Minor arc-green color tweaks (#25175)

Minor arc-green color tweaks (#25175)

Some minor color tweaks

<img width="1271" alt="Screenshot 2023-06-09 at 13 29 25"
src="https://github.com/go-gitea/gitea/assets/115237/b7b34995-5d34-461f-8d19-4f5755a98109">
<img width="1272" alt="Screenshot 2023-06-09 at 13 31 20"
src="https://github.com/go-gitea/gitea/assets/115237/63c866b4-797e-46ed-ba28-b1162ccd3e15">
<img width="1276" alt="Screenshot 2023-06-09 at 13 32 21"
src="https://github.com/go-gitea/gitea/assets/115237/de7ee02e-d0c7-4979-a8aa-0fd03e8db491">

Co-authored-by: Giteabot <teabot@gitea.io>