Resize message box

I have put the contact form into a widget and it looks very nice. It’s making the widget quite tall though. Is there a way to reduce the height of the main message box in half so that it doesn’t stretch the widget and make it so long? I’d like it to match the other widgets next to it.

Thank you!

https://ww.wp.xz.cn/plugins/clean-and-simple-contact-form-by-meg-nicholas/