The product slider on the home page have some issues. It is hard for me to determine if whether it is a css or javascript problem, but you can observe it even on your official demo: http://demo.snstheme.com/presta/sns-trella/en/

The things I have noticed under Firefox, Chrome and IE 11 are as follows:
1. The clock (countdown) plates seems to be very blurry (not sharp enough). The effect is quite unpleasant for the eye.
2. There is sometime left border of add to cart button missing. It show up after hovering any par of the product block (even the text). It also randomly (at least this is the impression byt maybe there is a pattern) shows up or disappears while sliding or clicking the next or previous buttons. The funny thin is that after reloading the page the missing border can be observed with every second picture.
3. There is also a problem with the font of Add to cart of the product slider module. While sliding (or going back and forth) the font seems sometime randomly switch from normal to bold and from bold to normal. This is another visual effect that for the end user looks like the page is maybe not loaded probably and should be refreshed.

It is the same in all 3 modules displayed on the home page.

I hope you can help me with this as those although a minor technical glitches can be a very serious problems for the viewers and customers.