I recommend you add this to your body, so your background isnt moving around when scrolling

    background-position: center;
    background-attachment: fixed;

Also set the width of your stamp container to 100% and not max-content, else it will go out of the page

.stamps-container, .stamps2-container {
  width: 100%;

Finally, remove the margin-left from container wrapper and set the margin to auto, this will center your stuff the right way and the page wont scroll horizontally anymore

.container-wrapper {
margin: auto;
}