@paulmartinb
Pretty close. After a bit of tinkering I figured it out. You probably already got it, but hopefully this will help someone later.
Put this in your child theme to prevent it from being deleted during the next update.
.site-header-half-width-logo{
background-image: url(https://customclouddatabase.com/wp-content/uploads/2014/04/Custom-Cloud-Logo-cropped.png);
background-size: contain;
background-repeat: no-repeat;
width:100%;
margin:0;
float:left;
My business website example using this theme:
