Header Z-Index = 2

logo

You probably can't read this part, so I will fill it in with useless text for the time being. This paragraph has a z-index of 1, which is less than the header. As you can see, the header has been moved down, using positioning, and is now resting on top of this paragraph. If we had not defined the z-index, by default the paragraph would have been on top of the header because it appears later in our HTML code.