slider over sidebars

Hiya,

I have installed the wowslider on https://suffolkholidaylodge.co.uk/ on the hueman theme.

however the theme sidebars appear under the slider on a smaller screen.

I have tried div and z-index, but to no avail.

Any ideas appreciated.

thanks.

https://www.ads-software.com/plugins/wowslider/