feedlink/blogpost templates: use class instead of id There can be more than one feedlink group in a page, as well as (more rarely) multiple blog forms, and using the same id for all of them causes HTML validation errors. Replace the id with a class by the same name and adjust in-repository CSS. (cherry picked from commit 0c3b91e1f06fb357711cfa71d514f139cd8e04e3)