I'm using the Delta theme. When I try to change the logo size (to make it larger), I'm not able to. The height seems to max out at 80 pixels. I think it's because of the header size.

@jasongeek
Open style.css and search for line starting with:
.logo {

try to change:
height: 46px; width: 220px; margin: 7px 0;
into:
height: 56px; width: 220px; margin: 2px 0;

How can I change the logo size (to make it smaller than the larger logo I've made) for the phone. I don't see an @media setting in the style.css.

I see height and width at 100%. Is that why I can't change the logo size on just mobile devices? Do you have any css to adjust the mobile logo?

i need to make the desktop logo large and the mobile logo small.

All media queries are in responsive.css.
You will find there .logo { line as well

Thank you.

Welcome 

I went into the responsive.css and changed the logo to two different sizes:
75%
50%

However it doesn't change it on the phone. I've attached two screenshots.