By default Publish online introduces a fade on page load even when there are no transitions applied in InDesign. This interferes when you use multiple pages to spoof the appearance of navigating within a one-page environment.

When I export to PDF the background isn't redrawn so the appearance of the linked page appears smoothly. Publish Online is clunky when loading the next page as it momentarily goes black and then fades-in the page items.

A bit of background .... I've created a page with a number of rollover buttons, then a duplicate of that page which is navigated to (x10) upon click release, to act as a navigable table of links for sections of a company assessment with one of our clients.