Add entering transition on Shop and fix some styling

- Center intro title vertically
- Cart item styling tweaks
- Add cart button quantity label inside of button so it's clickable

src/style/atoms/_button-cart.scss

@@ -8,6 +8,10 @@
         margin-left: auto;
     }
 
+    button {
+        overflow: visible;
+    }
+
     // Icon
     svg {
         color: #fff;
@@ -20,18 +24,20 @@
     // Quantity label
     .quantity {
         position: absolute;
+        z-index: 2;
         top: 50%;
-        left: -12px;
-        transform: translateY(-50%);
+        left: 2px;
+        transform: translate3d(-50%, -50%, 0);
         display: flex;
         align-items: center;
         justify-content: center;
         width: 22px;
         height: 22px;
-        font-size: rem(11px);
+        font-size: rem(12px);
         font-weight: 600;
         color: #fff;
         background-color: $color-secondary;
         border-radius: 100%;
+        opacity: 1;
     }
 }