Change colour of a single Megamenu item

[creative7]

I'm not sure if this is the right place to post this, I'm looking to change the colour or add a square background to a single Megamenu item.

I would like to change colour of the Choose Airline option seen on the top menu here: https://goo.gl/166tG8 (shortened link so real URL not indexed here)

 

Any help greatly appreciated, thanks in advance