Creating a clickable page background

You will need to copy header.php from your parent theme to your child theme and then edit the file. 



Below this add:

<a href="https://your-link.com" target="_blank" class="gp-takeover"></a>

Now go to Theme Options > Styling and in the CSS Code box add:

.gp-takeover {     
position: absolute;     
display: block;     
width: 100%;     
height: 100%;     
z-index: 1;     
cursor: pointer; 
.gp-site-wrapper {     
position: relative;     
z-index: 999;