Hi Helmut,
the class .container_header contains a padding-top with the value 4rem.
If you set this padding-top to a lower value in your custom.css you can shrink the space.
Original class (in one of my pages):
.container_header {
position: relative;
width: 100%;
z-index: 99;
transition: all 300ms ease;
padding-top: 4rem;
box-shadow: 0 1px 1px rgba(0,0,0,0.03),0 2px 2px rgba(0,0,0,0.04),0 4px 4px rgba(0,0,0,0.05),0 4px 8px rgba(0,0,0,0.05);
}
Add this to your custom.css:
.container_header {padding-top: 1rem;}
Replace
1rem with any other value you prefer.
I hope this helps.
Oliver