Fix SEO issues

[jakobkolb]

Describe the bug
this seo check sumary lists a number of critical issues on the page.

The most critical ones are very easy to fix (e.g. add or remove h1 headers)

[levino]

I would like to understand what the effect of this is etc. Please explain it to me in person once you have researched the logic.

[levino]

I think it is in order to call this a bug since these issues are reported as ERRORS.