Hi Martin,
To reduce the space you have to use the medium size logo OR you can add the custom CSS to reduce the space around the logo. For that go to Appearance -> Customize/Theme Options -> Design Options Tab -> Custom CSS paste the following CSS code and Click on Save & Publish button.
#site-title a img {
max-width: 220px;
}
#site-logo {
margin-top: 0;
}
.hgroup-wrap {
padding-bottom: 12px;
padding-top: 10px;
}
Thank you for using our theme.