How to CSS Success message?

When a user enters an email address they see a “working” bar and then a success message.

My problem is that I’ve styled the input and submit button so that it sits at the bottom of the popup. The working bar and success message display below it, if I want a bottom corner popup the message displays off screen and the user doesn’t understand what’s happening.

Screenshot:

What element, id etc would you target to style this and bring it up into the popup?

Eg page: http://goodonyou.staging.kinsta.com/shop-ny-fashion-week-trends/
Thanks

https://ww.wp.xz.cn/plugins/dreamgrow-scroll-triggered-box/