Will This Be Structurally Sound?

I would like to build a cat enclosure on my deck, but the catch is: I'm renting so it has to be a standalone frame. I appreciate all feedback as my building experience is limited to Ikea furniture

I not fussed about how it looks, just want to know if this thing will be strong enough to hold itself together. Measurements below:





I have "designed" a wooden frame from 70mm x 35mm treated H3 structural pine, as it's relatively affordable (but I'm also open to suggestions). I was planning to use wood screws where each bit of timber meets. (again open to tips).

The deck is also aged so I'm worried about putting too much weight on there, which is also why I've picked this timber.

Total measurements are 3600mm length, 2800mm width, and 1935mm height.

Will this thing be strong enough, or will be wobbly or collapse easily?

Thanks for reading and thanks for the help!

Well I've updated my design - any feedback welcome

It needs to be cross braced, or the corners made more rigid.(say have a diagonal section at each corner about 1m down the post to about 1m along each post.

Excellent, thanks