<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=391616) </details> <!--IssueSummary end--> As a follow-up to https://gitlab.com/gitlab-org/gitlab/-/merge_requests/108262+, where we updated the style of selected and commented lines in MR diffs. The commit diffs were slightly affected by those changes, and the blob/file view was not changed at all. This was an intentional deviation from the specs of the [original issue](https://gitlab.com/gitlab-org/gitlab/-/issues/384074), as commented in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/108262#note_1270884521. This issue is to maintain consistency between the different file views and their style of selected lines.