I have set the background on #container_header to transparent, as I have included a colored angle behind the logo (similar to the Riley template):

https://www.midlothianlibrary.org/homepage-2

Once scrolled, the white background is added to #container_header. However, during the scroll transition, I can see the content of top-1a and top-1b (slideshow and news areas) behind the header content until the scroll is complete (see attached). How do I change this so that the white background is added immediately?

Thank you.