Use / for url

_config.yml

@@ -13,7 +13,7 @@ description: > # this means to ignore newlines until "baseurl:"
   line in _config.yml. It will appear in your document head meta (for
   Google search results) and in your feed.xml site description.
 baseurl: "/jekyll" # the subpath of your site, e.g. /blog
-url: "https://pages.gitlab.io" # the base hostname & protocol for your site
+url: "/" # the base hostname & protocol for your site
 twitter_username: jekyllrb
 github_username:  jekyll