@manfred: This is not a theme issue but two plugin conflict. There is conflict between Jetpack plugin css and Slick-doc-it plugin css.
For example your social links width padding is overwritten by Slick-doc-it plugin css. So, you need to do force padding by adding the following css in “Appearance => theme Options => Custom CSS” box.
.sd-social-icon-text a.sd-button > span, a.sd-button > span {
padding: 1px 5px 1px 23px !important;
}
Next for the page http://www.picture4you.nl/test/kennisbank-test/, I recommend you to remove the first social link from the top and just add in below only. Again there is conflict between two plugins. So, try adding the following css “Appearance => theme Options => Custom CSS” box to force fix it.
#primary #content .sharedaddy {
clear: left;
display: block;
float: left;
width: 61%;
}