Urban Huntress on "[Theme: Oxygen] Left sidebar is not as "responsive" as other content"

Hi there,
Widgets in the left sidebar seem to just go behind the main content and overlap it in some cases when a window size is a bit small (like on the iPad), but not small enough to force it into one column. It seems to me that the issue is in the responsive settings for the left sidebar.

I don't know what to do about this. Any suggestions?

Thanks