title: Customers can add variation to cart even when drop down menu not selected
body: <p>I run a website that sells variants of the same product, allowing customers to select from a drop down menu to choose which one they want. <a href="https://theapiary.co.nz/shop/skin-care/skin-care-cream/" rel="nofollow">In this case</a>, choosing between 125ml and 250ml. </p>
  
  <p>The problem is, customers can add a product to their cart, even if no size has been selected and it still says Please Select in the drop down field. In this case, the Starting From price will be added to the cart, and if a transaction goes through I have no way of knowing what size they actually wanted.</p>
  
  <p>Is there any way I can block their ability to Add to Cart until they make a selection?</p>
  
  <p>Thanks in advance.</p>