Fix detectable accessibility violations on /advantage

[sowasred2012]

Running the Cypress accessibility tests reveals a few issues:

[elioqoshi]

@petermakowski do you know which specific colour contrast issue this is referring to?

[petermakowski]

@petermakowski do you know which specific colour contrast issue this is referring to?

I think it's only within navigation, e.g.:

[elioqoshi]

@petermakowski Ah that's the Ubuntu brand colour which is not AA compliant. Maybe @lyubomir-popov or @long-chung can chime in?

[carkod]

Advantage no longer exists