I am composing a cover letter and I was provided a blank pdf page with the letterhead. I followed some suggestion and used the wallpaper package as follows:
I only used the letterhead for the first page. It turned out that the background color of the letterhead page is different from the default color in later pages due to the original letterhead file.
I wonder if there is a way to make background color uniform; either the color of the letterhead file or the default color is fine.