ecommerce product page with html ,css and javascript

Hi! There are some issues.

1. When I try to add quantity into my cart, suppose I entered 5 quantity, then instead of adding 5 more it only add 1 quantity.

2. In Mobile view your corousal is going outside the viewport.

3. In Mobile view black overlay not taking complete width and the cart little quantity circle also moves right and left on menu hide and show.

4. Text is too small to read data.

Too many other issues are there, please fix them all.

Good Luck !