add some meta tags
comply with html standards
image/x-icon is not a valid MIME type. the valid MIME for ico files is image/vnd.microsoft.icon.
the .ico file also contained 3 sizes (which we don't really need), which were poorly resized. One of the sizes actually had glitches, see https://i.imgur.com/OGWpggH.png

the /favicon.ico file remains, but contains only 1 image. The link/icon meta tag complies with the standard defined at
https://html.spec.whatwg.org/multipage/semantics.html#rel-icon. It links to favicon.png using image/png.

The ico file has been compressed to 1.1KB and the PNG is 0.5KB.
fix jade markup, link to #, remove commented code
fix link -> meta tag
add alt tags to images
fix content margin-top
floating header is 50px and has a 20px margin-bottom (which is obviously not applied)
we don't need serve-favicon