@Sebastian: You can change the margin as per your wish. Just add the following CSS in “Appearance => Theme Options => Custom CSS” box.
/* General */
#secondary .widget { margin-bottom: 40px; }
/* For screen size above 1190px */
@media screen and (min-width: 1190px) {
#secondary .widget { margin-bottom: 50px; }
}
/* For screen size below 1160px */
@media screen and (max-width: 1060px) {
#secondary .widget { margin-bottom: 30px; }
}
/* For screen size below 960px */
@media screen and (max-width: 960px) {
#secondary .widget { margin-bottom: 20px; }
}