http://dtn.zynnoitestudios.com I'm using a SVG logo

http://dtn.zynnoitestudios.com

I'm using a SVG logo and I would like to understand how to make the SVG logo about 20% smaller in the header. I'm having a hard time understanding how to work with SVG sizing.

Is there there a way to enter Custom CSS to make the SVG logo 20-30% smaller.

Thanks JIM