Hello,
Please add following given CSS code in Additional CSS section to remove the blue area at the right hand side of the image by going to Admin Panel > Appearance > Customize > Additional CSS
#header-image img{
max-width: 100%;
}
Also, to reduce the height of the image, please add following given CSS code in Additional CSS section.
#header-image img{
height: 527px;
}
Further, you can replace ‘527px’ with your desired pixel.
Hope this helps.
If you have any queries further, let us know.
Thank you.