Improve OWID's accessibility lighthouse score

[ikesau]

Core problem

Across various pages for both desktop and mobile, we're "leaving accessibility on the table" by having buttons without roles, insufficient contrasts, non-hierarchical headings, and missing attributes.

On Desktop, many of our pages hover around 85-90%

On Mobile, most pages are closer to 80%

Proposed solution

Dedicate a day and a dev to running WebAIM's WCAG Audit and Google Lighthouse to fix as many of the easy issues as possible.

Alternatives

A more robust and exhaustive personal WCAG 2.1 Level AA audit could also be done.

Context

[larsyencken]

Chatted to Daniel B, possible we could pick this up just before Sicily, if it doesn't get done in a cooldown before then.

[larsyencken]

Proposed in Dev slack channel to do it together next cooldown