Good afternoon Sherman and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
I would love to help you with this topic.
You are right, it does look like Avada’s styling of the quantity boxes needs some reviewing.
I would recommend letting them know. They are usually pretty responsive for that type of thing.
Try adding the following CSS rule to your style.css file or in your Custom CSS metabox:
.tribe-events-style-full .woocommerce .quantity input {
width: 30px !important;
}
Let me know if that helps.
Have a great day!
Geoff B.