Accessibility: headers not in sequentially descending order

[hugovk]

We have no H1 header.

The cards use H3 titles, with H5 subtitles.

We should probably put "Translation Dashboard" in an H1, and change the H3->H2 and H5->H3.

https://www.accessibilitychecker.org/wcag-guides/ensure-the-order-of-headings-is-semantically-correct/