Use same horizontal size for IDP login and consent

frontend_src/_custom.scss

@@ -35,16 +35,9 @@ body.idp {
   padding-bottom: 40px;
 }
 
-.form-signin {
-  max-width: 330px;
-}
-
-.form-consent {
-  max-width: 550px;
-}
-
 .form-signin, .form-consent {
   width: 100%;
+  max-width: 550px;
   padding: 15px;
   margin-left: auto;
   margin-right: auto;