Last resort. Please help! Customers cannot add items to their carts.

So I have a site http://mybundlesboujee.com. And have been facing this problem since I launched my site in March. The problem is that some (mainly Iphone users) cannot add items to their cart. So if they select their color, and their length and hit "add to cart" or "checkout now", nothing happens. Now, if I visit that same page, I am able to checkout with no problems. As well as all the customers who have successfully made purchases on my site.

The craziest thing about this is that I have tried to hire multiple web designers, and they cannot help because they say they cannot recreate the error. I even contacted the creator of my theme and he believe it's an error on the customers behalf, but I know that is not true. This is the reason why.

So customers who cannot add items to their carts says that they can indeed add an item to their cart if they select the options in black text (I included images below), but if they select the options in purple text and hit add to cart, that's when nothing happens. BUT no option text should be purple, I don't even know why any text is displaying in purple text on any device! All the options should be in black text! And I believe that's were the problem lays! It's just trying to figure out the exact problem that's the challenge I suppose. I have attached a screenshot below of what customers are seeing when they are on the product page before hitting the add to cart button.

Please view this image
upload images

And here's how it displays on my device.

Please view this image

Please if anyone could help, I would greatly appreciate it!

My site is on Opencart's platform version 2.3