Layout of login and signup pages is kind of broken on mobile devices.

Users, who sign in or sign up from a web application, have to visit these pages. Even when the application looks great on mobile, this can ruin the experience.

Therefore, would it make sense to display these pages properly on different screen sizes, e.g. with media queries? Or can application developers control looks of these pages? Or server administrators? Or both?

Even if it's customizable, it would be great if there is a properly working default.

Here's screenshots of what i mean, please notice the horizontal overflows: