Widget in footer. Hide on mobile landscape

Dear all, meanwhile my website is online:

Now you see this marketing widget in the right bottom corner. Here, I put the pure code into a separate plugin (Header Footer Post Injection), which probably is not the best way. What I want to achieve is that this widget is NOT shown on mobile landscape. So how would I do it the right way?
I thought about creating another div in the footer, then Rich Text, then the code. It should then be possible to hide this element according to needs. But I didn’t manage to make this work.
A little guidance would be great.

Hi Laic,
It looks like you have an error establishing a database connection, I can’t check the widget in detail.

Kind regards,
Matthias

Thanks. Fixed now. Best regards.