Your site looks great!
Take a look for this code – position: fixed;
in your style.css file around line 1156 –
/* # Site Header
---------------------------------------------------------------------------------------------------- */
.site-header {
background-color: #fff;
border-bottom: 1px solid #ddd;
left: 0;
position: fixed;
top: 0;
width: 100%;
z-index: 999;
}
Depending on how you edit your CSS, you can either remove that line, change it to position: relative;
or add your own Custom CSS code to override it.
If you plan to add your own Custom CSS code, you can try adding it to the Customize > Additional CSS page in the customizer like this –
.site-header {
position: relative;
}
That may open up some space on the homepage under the header. If it does then you can adjust the margin-top (140px) around line 631 in your style.css –
.site-inner {
background-color: #fff;
clear: both;
margin: 140px auto 40px;
position: relative;
z-index: 9;
-word-wrap: break-word;
}
Let me know if that works.