I experiment a little and added this to the CSS file:
.site-title {
background: url("https://boutiquegardenvillas.com/wp-content/uploads/2015/09/logo-bgv.png") transparent;
color: transparent;
height: 134px;
width: 735px;
And the logo is now on the place were the title text was.
But the logo image is not resizing when I make the window smaller.
Everything from the website is getting smaller if i shrink the window but the logo stays the same size.
I hope somebody have a solution for me.
regards Alan