SVG Logos on login screen need max-width

[bacoords]

Reminder to add max-width: 100%; in setup.php

[bacoords]

Reopening this because max-width doesn't solve the fact that $image = wp_get_attachment_image_src( $custom_logo_id, 'medium' ); returns the full width image, so the dimensions are all wacky. It might be better off with a generic square size and just using background-size:contain