HOMEPAGE: Heading elements are not in a sequentially-descending order

[chuckcarpenter]

Properly ordered headings that do not skip levels convey the semantic structure of the page, making it easier to navigate and understand when using assistive technologies.

H2 -> H5

[RobbieTheWagner]

We probably used some of these just for margin/padding, back in the day, but agreed we should fix this.