Door Buddy Door Prop for Cats - Easiest Cat Door Latch Holder to Keep Interior Door Open for Pets - Dog Proof Cat Feeding Station & Litter Box - Strong & Portable Door Stopper & Pet Gate Alternative

Do you have room for a play pen instead? I got a retractable gate with mesh and my daughter learned to army crawl underneath it (genuinely thought there’d be no room for her to be able to do it but she did 🫠) pretty quickly and we stopped using it. If you can’t just keep the basement door closed then I’d suggest something like this that will keep it ajar but too small for baby to squeeze through. We have to keep ours open for cats to get to their food/litter down there and this has kept her out!