Widget column displays wrong in Kubrick theme

Newbie here. Just setting up a site at https://www.escondidodems.org/wp and cannot understand why the widgets column to the right displays way down below the posts text, as if it has been crowded out of a frame or somthing like that.
I notice the same issue on another WordPress blog at https://www.democratictalkradio.com/wordpress/?p=934
Can anyone offer any advice on how to fix this? Thanks!