155 remastered about us

[XwayTomy]

Summary

Visual upgrade to welcome- and about-us page. The text is now centered on both pages and scales according to the window size. Furthermore, the registration button is now enlarged to make it more easy to click.

https://user-images.githubusercontent.com/73949081/169372883-6ef69b34-4cb5-44ec-8089-077a7619f81f.mp4

Definition of done

• [x] All acceptance criteria are completed.
• [x] The code has (at least) 80% branch test coverage.
• [x] All tests pass.
• [x] The code is reviewed and accepted by (at least) two other team members.
• [x] Views adhere to design style.

Closes #155