I tried a few other things, and have been able to see the problem you're describing.
It's caused by your javascripts. If I tell my browser to ignore javascripts, and then scroll down your HTML page to the prices links and click one, it loads the store with the stylesheet immediately. Never any need to refresh.
Looks like your javascript is interfering with normal page loading, causing the next page to NOT actually load at all (judging from the browser Inspector), until you do an explicit refresh.
Start by removing all your javascript, and then add things back one by one, keeping only the essentials, until it breaks. Then you'll know specifically what's causing it.
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