Here are the main guidelines for the logo image, which you can set in Theme Options » General tab.
No matter the dimensions of the image you upload, the theme will always limit the height or the width of the logo to make it fit into the header. That limit depends on which Header Height setting you’ve chosen (Theme Options » Layout tab » Header Options).
Limits the height to 40px.
Limits the height to 80px.
Header Layout 7:
The only exception is Header Layout 7, which doesn’t have an optional height. This Header Layout limits the width of the logo image to 100% of the header container, but doesn’t limit the height.
To get the best results, upload an image that has the same (or a bit bigger) height and width as the limits on each layout, but never smaller than that.
If you also want to upload a version suitable for retina devices, then the size should be twice as big as the regular one.
We recommend using PNG with transparent background.