Fix searchbar in navbar

[hofbi]

• [ ] On wide screens the searchbar should be aligned on the right. On the left side we should have our icon an page name, followed by the nav icons.
• [ ] On small mobile screens the searchbar should always be visible. Just the nav icons should be collapsed.

References:

• https://stackoverflow.com/questions/39060926/fixed-search-box-in-bootstrap-navbar

[hofbi]

Outdated since swicthing to mkdocs