Widgets ovelaying

Hi. I would really appreciate your help regarding 3 things:

1.) I have a problem with widgets in the sidebar – they are overlaying when I`m scrolling down the page. I tried position:static and position:relative but nothing seems to work. Can you help please?
I can send a photo if you will not be able to reproduce the problem (just let me know where to send it to).

2.) When I hit the top of the sidebar (while scrooling) margin between widgets (PROJEKTI & LATEST NEWS) changes – the same thing happens when I hit the footer (footer “is the stop ID”).

3.) It seems like the widget is jumping while scrolling on the page. Sometimes the widget is under the navbar and submenu (I have set top margin at 100px and bottom margin at 25px). I would like to accomplish that the sidebar gets sticky once it touches the submenu (+ 10px top padding or something like that)

Thanks!
MB

The page I need help with: [log in to see the link]