Mobile responsiveness isn't working

I have a standard marketplace with products in a RG.
4 columns.
When I go on mobile the screen gets all stretched.
So I’ve set it so its only 1 column.

But when I check in on Mobile it doesn’t change.
What is going wrong?

Are you sure that your page is exactly 320px wide?
I suppose you’d like to apply responsiveness when page width is equal or less than 320px, not when it is exactly 320px

Same issue when I do this:

The default value for mobile on Bubble is actually too low.
Phones have gotten bigger and have a better pixel resolution than what they did when that value was set.
For example, my phone is 375 px wide, and its not even particularly big.

Either just put a bigger number than 320, or set a custom breakpoint which is greater than 320. It doesn’t need to be related to how big your phone is. Set it to the width below which your repeating group starts looking bad.

I would recommend putting a ‘Current page width’ text somewhere on the page. It helps when dealing with responsiveness. Remember to remove it once you are finished with developing responsiveness.