gc-featured-link: adding bg color option

[Garneauma]

Adding option to customize the background colour of featured links.

Added CSS to hide the customized link by default to prevent a colour flick on load.

[GormFrank]

Partial review

[duboisp]

• This is broken in basic HTML mode, we should still display the featured banner. In basic mode I can see a white text with a white background.
• How do we ensure the text inside the banner do have and maintain a sufficient contrast ratio? Should we auto switch the text color between black and white depending of the luminosity of the background color that was set?

[Garneauma]

This is broken in basic HTML mode, we should still display the featured banner. In basic mode I can see a white text with a white background.

Adjusted to only add the white background on standard version.

How do we ensure the text inside the banner do have and maintain a sufficient contrast ratio? Should we auto switch the text color between black and white depending of the luminosity of the background color that was set?

If you look at the example, there is the following alert:
"Accessibility consideration
Make sure that the background color has enough contrast with the text as required by WCAG 1.4.3."

[duboisp]

I love the way it is setup and do self-adjust to ensure it meet the contrast ratio.

[duboisp]

Testé localement et ça fonctionne tel que prévu, il va rester à adjuster la couleur du texte par défaut juste avant que l'initialization soit complété.

[duboisp]

Pre-approved upon the default loading style in standard mode do have sufficient contrast ratio

[duboisp]

Tested locally and reviewed. Every work as expected.

was addressed