[Theme Mystique]: Resizing logo in header

My site, https://www.parentingaces.com, uses Mystique theme. I finally figured out how to use my logo instead of text for the header but am now trying to figure out how to make the logo appear a bit smaller since it seems to take over the majority of the screen. Can anyone help me with that?

Also, there appears to be a broken image in the top left corner of the header now, and I can’t figure out what it is or how to get rid of it – any advice???

Thanks!