Close pop up form and gap in signup form

Replies: 0

Great plugin but I’d like some help.

Please take a look at this page …

https://wemuster.co.uk/

I would like to change the colours on the “Contact Us” button to all white
Is there a way to add custom CSS somewhere?
In the sign up form, there is a gap between the email field and the subscribe button, how do close that gap.
On the popup form, Id like an x just outside the popup form so there is a visible way of closing the pop up form.

Please help. Thank you.