Strengthening a shoe rack

[Kevin92]

Decided to build a custom shoe rack to fit the space we have. Everything came out well however it’s not very firm as it sway left to right easily when it’s touched. Do you think I should add more firm shelves or fix a sheet to the back? Or is there anything else I can do to make it firm

[LePallet]

@Kevin92 You beauty, nothing but good news to start off the week