Compost Bin by GEOBIN https://www.amazon.com/dp/B010V673AC/ref=cm_sw_r_cp_api_i_c6YSDb03DWX0M

This is a very easy and inexpensive solution. I have this one, it took me 5 minutes to set up.

As for browns, easiest thing would be to shred up some newspaper and mix it in with the grass clippings. That combo will break down very quickly.

Take a look at Geobin on Amazon and elsewhere. They meet your specs. Look decent and do a good job. I have 3 of them.

Here's a link: https://www.amazon.com/BanKhok-Geobin-Compost-Bin/dp/B010V673AC