In order to create a seamless effect/illusion for a background, avoid having any objects or graphics near the top or bottom. This will avoid the chance of any elements being cut off due to the different page lengths.
Tip: Creating a long background? Learn more in the "How to create a background image for a longer page" article.
1. If doable, ensure the background image does not have graphics that "bleed" at the top edge or bottom edge.
Shift these graphics so it sits close to the top but does not "cut off". Note that graphics can still bleed on the sides. Play around with the background image so that the side spaces are being utilized.
Tip: Be cautious of how wide and long the text box sits.
2. If your background image MUST include graphics that bleed off the top or bottom, your best bet is to ensure that the size ratios of all graphics are the same across all backgrounds.
Important Note: This method may not translate on mobile.