Change Widget Length, Size, Etc?

Hey Friends.

I have the contact form 7 mailchimp extension as my primary sidebar widget.

I’ve managed to change a few things on my own, but want to change the length of it. It’s too long.

Here’s what I have at the moment:

/* Sidebars Widget */
.sidebar .widget {
font-size: 20px;
color: #FFFFFF;
background: #0073AA;
}