Unlabeled links and missing page headings
As a visually impaired person using Gitlab-ce with a screenreader, I noticed that some links (such as the ones on the very top menu for logout, new project, admin), aren't labeled properly - that is, with the normal HTML syntax, which makes it difficult for screenreaders to announce them properly.
Also, though there are headings for the top navigation bar, and the menu below that, there sometimes is no heading below those to denote the start of the content. An example of this would be the tags page of a repository. The 'New issue' page, however, is properly labeled.
Having elements properly labeled and with headings would greatly increase accessibility for gitlab, as well as eliminate some layout inconsistencies.