Various Floating Social Buttons improvements

[benlk]

Changes

• Fixes issue where floating social buttons were not clickable, because of z-index ordering. issue #1576.
• Fixes links in social media buttons not respecting the blog's character set. issue #1283.
• Function largo_post_social_links now respects the blog character set option. issue #1283.
• Increases the text-to-background contrast of the post social media buttons and their popover menus:
  • Darkens button icons from @grayLighter to @gray, which is from #dddddd to #7D8185 against a #ffffff background. This is actually a little bit short of the required contrast ratio; this change bumps it from 1.36 to 3.92, but it should be at least 4.5. The next step on our color scheme is @grayDark, #484848, at 9.15 contrast ratio.
  • Removes some duplicative a coloration rules already present in the cascade

This image shows the z-index change, meaning that floating social buttons float over wide images and full-width images, but are now clickable:

The above image also shows the old contrast levels.

Here's some samples of the new contrast level:

Questions

@tylermachado, should we go all the way to 4.5 contrast ratio? If so, should this be through adjusting @gray (would require a review of the use of that color all across the theme) or should we define a new color?

Why

Because I was examining this section of code for INN/umbrella-freshenergy#21 anyways, while discovering #1634

Change the button color to make them meet the WCAG AA standards for contrast.

[benlk]

Tyler Machado [10:31 AM]
merge away

i think the contrast ratio is fine for this case