Preview mode to the rescue! Preview allows you to check your site design and customization changes before you publish those changes for your guests to see. To see how your design changes will look, log in to your site, go to Site in the navigation bar, then click "Customize Design." Make the changes you'd like to adjust, then select "Preview."
Please note that you'll see your Unlisted (Anyone with the Link)and Private (Only Me) galleries, folders, pages and photos in the preview because you're logged in to your site as the owner.