I see what you mean. I’ve added some updated CSS here that will fix this, but there is just one extra step.
Due to some technical issues, this CSS needs to be added with the Simple Custom CSS plugin, instead of being added via the Custom CSS section in the Customizer.
You can remove the prior CSS from the Custom CSS section, and then place the code below in the input provided by the Simple Custom CSS plugin:
@media all and (min-width: 800px) {
.sidebar-after-post-content .widget,
.sidebar-after-page-content .widget {
width: 50%;
float: left;
}
.sidebar-after-post-content,
.sidebar-after-page-content {
border-bottom: none;
}
.sidebar-after-post-content:after,
.sidebar-after-page-content:after {
content: ".";
display: block;
clear: both;
visibility: hidden;
line-height: 0;
height: 0;
}
}