Field Height in Forms

Hi,
First of all, thanks for a great plugin. Seems to be meeting all of my needs. Lots of options for customization provided. Love that.

A question: how do I format the forms to get thinner fields? I do not mean the field width, which I know I can change. I mean the height of the fields. To make them more sleek.

Also, what is the div class for the forms if I want to experiment with styles of different aspects of the forms (such as font, font size and color?

https://wordpress.org/plugins/ultimate-member/