Rendering error in layouts/layout.html.

Home renders with a purple box around it, but not in white text. When focus is changed to the about page, the purple box does not move with it. Better functionality would be white text for both links, and a larger purple box that moves with the current page.

Noticed:
- Raspberry Pi Stretch with Chromium.
- Ubuntu 18.04 with Firefox.
- Please comment below if noticed elsewhere, or other behaviour noticed.

The issue names layouts/layout.html; start by opening that template and reproducing navigation between Home and About in one of the listed browsers. Done means both links use white text and the larger purple focus box moves to the current page.

Vom Indexierungsmodell aus dem Issue-Text verfasst.