Hey @mwagner,
Looks like to me that your header is transparent and the max-height of the logo is set to 0 on scroll.
Without looking at the backend of your site I'm not too sure how this has occurred. But you can add the following to the CSS:
/* change header to white */
#header {
background-color: #fff!important;
}
/* keep max-height of logo */
.logo-image.header-hidden #header .logo {
max-height: 100%!important;
}
