Dark Mode Fix - New User Registration - Welcome to GitLab Screen

Problem

Currently with the new role out of Dark mode the Welcome to GitLab page in new user registration looses the card border when shown in Dark Mode.

The card should leverage a token that enables it to work in Dark Mode, preferable border-color-default . A goal would be for it to appear similarly to the "Tell us about your company" screen and the ensuing screens.

This occurs in both Trial & Free User registration.

Light Mode	Dark Mode