Fix active state on action link

[alex-ju]

What

Fix the active state on the action link component by simplifying the styling and rely on default anchor styling for the active state (as we do for any basic links across GOV.UK and within the Design System).

Why

Causes issues when used in the light_text flag.

The component used in the site-wide banner in Safari 14.0:

Thank you @conordelahunty for reporting this!

Visual Changes

Before `:active`	After `:active`

Preview link

[maxgds]

Is there any chance this could be a breaking change? If somebody is relying on black and hasn't set anything elsewhere might they wind up with unexpected colours and poor contrast?

[alex-ju]

Is there any chance this could be a breaking change? If somebody is relying on black and hasn't set anything elsewhere might they wind up with unexpected colours and poor contrast?

Mmm, not really. The light_text option is meant to be used on darker backgrounds (dark blue #0843a1, dark grey #272828, and more recently on black #0b0c0c). In any of these scenarios, we wouldn't rely on the active state to be black #272828 as this would result in low contrast (or no contrast as it happens on the homepage).

If the component is not used with the light_text flag, the link colour for the :active state will remain #0b0c0c