Variant Drop Down on Mobile

Site URL: https://www.urbanpawspets.com/

I added a variant drop down to my website. On mobile devices, clicking the variant drop down automatically zooms in the screen, forcing the user to readjust the screen after selecting a variant. Any CSS code to fix this? 

Also, is there a way to adjust the "width" of the variant drop down button on desktop view? Right now the width is the entire screen which looks a little bizarre. 

Thank you.