Broken styles in db-mainnavigation

[d-koppenhagen]

Starting from version 0.29.0, the styles seems to be broken

❌ v0.29.0 (Broken)
https://db-ui.github.io/elements/version/v0.29.0/?path=/docs/02-navigation-main-navigation-intro--docs

✅ v0.28.0 (Broken)
https://db-ui.github.io/elements/version/v0.28.0/?path=/story/02-navigation-main-navigation-intro--page

[mfranzke]

we need to reevaluate this topic after we've migrated our header styles by newer changes anyhow:
#2709