That worked, but it seems only the shop related pages needed to have their margins tinkered with. Other pages should stay as they were. I used this code to make it work, but am not sure if that’s the right way to do it. Please, check the code and let me know if there’s a better/more practical way.
/* Add 40px margin to the whole website */
.main-page-wrapper {
margin-top: 40px !important;
}
/* Remove the margin for the specific pages */
.page-id-3669 .main-page-wrapper,
.page-id-4400 .main-page-wrapper,
.page-id-4439 .main-page-wrapper {
margin-top: 0 !important;
}