No worries. I was just surprised that it changed themes when I was in the middle of working on it. And feel free to try different themes, you may find something better suited to your site. In fact, I would recommend a theme from the WordPress theme repository, because those themes tend to be kept up to date with the latest security patches, and they follow standards that are set by WordPress.
That last URL you posted is perfect because it doesn’t have cropped in the name.
Now, I see that you have Jetpack installed, so first activate Jetpack’s Custom CSS option by going to Jetpack → Settings → Appearance, then scrolling down and turning on Custom CSS.
Then go to Appearance → Edit CSS and copy & paste this rule to the end of the CSS Stylesheet Editor:
header .header-inner-site-branding {
background-image: url('https://brocksbooks.com/wp-content/uploads/huge-header-2500-DL.jpg');
}
@media screen and (min-width: 480px) {
header .header-inner-site-branding {
padding: 80px 0;
}
}
@media screen and (min-width: 600px) {
header .header-inner-site-branding {
padding: 150px 0;
}
}
Your site will now use the full sized, full resolution image instead of the cropped one.
If you do happen to switch themes, note that there’s this note on the page: Note: Custom CSS will be reset when changing themes.. So copy the CSS somewhere where you can paste it back in if you want to come back to Zillah, or you can also click one of the links on the right to restore the CSS.