Hi,
This problem has been discussed many times in the forum and solution has been provided. So, here is the solution:
1- open this CSS file:
/templates/purity_iii/html/com_virtuemart/assets/css/flexible.css
2- Scroll to the very bottom and insert these lines:
span.FlexibleCSS3ButtonQuantity {box-sizing: content-box;}
.FlexibleCSS3ButtonQuantity .quantity-box { width:60% !important;}
.FlexibleCSS3ButtonQuantity .quantity-box input.quantity-input { width:100% !important;}
and you will be good to go.
FYI: DON'T FORGET TO REFRESH THE CACHE VIA JOOMLA BACKEND
The result will be:
Attachment ScreenShot2016-09-23at8.52.27PM.png not found
Regards.