Resizing of number input fields doesn’t work

Hi there, thank you so much for this plugin, it helps me so much with my website!

I have tried to resize the width of the number input fields as the input is sometimes a 4 or even a 8 digit number and only 3 digits are visible. I tried it with css but nothing works. Maybe you have a solution for this?

Thank you very much, greetings from Berlin!

The page I need help with: [log in to see the link]