Fix Accessibility Issues

[Dunn-Austen]

Background and foreground colors do not have a sufficient contrast ratio.
The yellow color we're using is now getting flagged in the accessibility audit.

- h2.date
- p.subtext
- p.subtext
- p.subtext
- p.subtext

Html element does not have a lang attribute

Some elements have a [tabindex] value greater than 0

Items to manually check
- The page has a logical tab order
- Interactive controls are keyboard focusable

• Interactive elements indicate their purpose and state
  - The user's focus is directed to new content added to the page
  - User focus is not accidentally trapped in a region
• Custom controls have associated labels
• Custom controls have ARIA roles
  - Visual order on the page follows DOM order
• Offscreen content is hidden from assistive technology
  - Headings don't skip levels
• HTML5 landmark elements are used to improve navigation

[hfaerber]

We will need to examine the tab order once the post form is merged to ensure the user is able to tab through and doesn't get stuck in the process.