Change Action Bar height

I think that the height of Action Bar is too large for my blog. I did change the headline message size by adding this to custom code CSS:
#ig_this_message .ig_headline{font-size: 0.75em !important;}

But how can I change even the size of e-mail address text field and the submit button and it’s label?

Thank you
blog.tropicsathome.com

https://wordpress.org/plugins/icegram/