Elements should have sufficient color contrast (followup)

[akslay]

Problem/Motivation

Related to #309

The horizontal rule element stays the same color regardless of background color, making it inaccessible on darker background colors.

Proposed resolution

Add the <hr> tag to the SCSS that ensures proper color contrast; it should match the color of the text.

In general, might need to just throw every possible element on a dark background color to make sure we caught everything (I'm coming across these as I add elements to the CKEditor in AZ Quickstart 2.0).

[trackleft]

Is there an WCAG recommendation for this?

[akslay]

I didn't find anything about horizontal rules specifically on WCAG, but I would think an <hr /> should have the same level of color contrast as text, right?

[akslay]

Another item that needs to leverage the built-in color contrast: text inside tables.