How can I increase the width of my text box

Hey guys,

I seem to be running into a problem when I am using the short code as in this page on my test site: https://www.live-yoga.online/yogic-management-of-obesity/

The width of the text box appears to be too small to accommodate more than one number.

I was hoping you can help me out on this.

Thanks and Regards,
Vinay

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