This is really great! I really think that your design choices make the site accessible and do a good job of directing the viewer’s eye.
On my macbook (about 600px x 1200px), It might be nice to give a bit more distance between your picture and the header, but that might just be me! I also think that your logo text and image might benefit from being center aligned.
I also notice that your text and logo seem to get left behind when I scroll down so they don’t show up on your header further down the page.
I hope that’s helpful! It looks really great!