Backport #30707 by @silverwind Fixes https://github.com/go-gitea/gitea/issues/30673, all 23 issues. Notes: - Tab bar menus had to change to pills because of unsolvable issue with the border-radius as tab bar renders a overlapping border onto the box below. And I think pills look better. - Added padding to code editor empty preview message - Hide monaco's built-in blue focus border, we don't need it and it never showed before either. - Label add menu is simplified, removing the nested segment. <img width="1322" alt="Screenshot 2024-04-25 at 22 26 19" src="https://github.com/go-gitea/gitea/assets/115237/7e394e0c-b7ad-417d-8e9f-12f1dea93ed1"> <img width="1326" alt="Screenshot 2024-04-25 at 22 28 00" src="https://github.com/go-gitea/gitea/assets/115237/66c8499f-aa9f-4d95-8cca-ef13dfa82c65"> <img width="997" alt="Screenshot 2024-04-25 at 22 36 53" src="https://github.com/go-gitea/gitea/assets/115237/07896102-c71d-4246-8173-c2bc2e1d3cae"> <img width="832" alt="Screenshot 2024-04-25 at 22 56 09" src="https://github.com/go-gitea/gitea/assets/115237/d83afc96-08ca-4adc-baf4-3d02804be57c"> <img width="361" alt="Screenshot 2024-04-25 at 22 57 12" src="https://github.com/go-gitea/gitea/assets/115237/c7371a68-00b5-47d8-84d0-ddc5268b2b2c"> Co-authored-by: silverwind <me@silverwind.io> Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
