7.0 Brine header background image is cropped on initial load

This is a small but annoying issue on my client's site. On initial load, the background image in the header appears cropped and doesn't extend all the way behind the header text block. See screenshots. Is there something I can do to force load the image all the way to the bottom of the header block?

First screenshot shows how the page first looks. 

The second shows how it should look, and how it looks after reload.

Thanks for any tips!

What is page url? We can check easier