Use a linear gradient for a background. Set the outside colours to the same as the next background section, and the inside colours to something darker.
If you want to divide two sections of a page, you can use a gradient like this to do it. It creates a harder divide in the middle of the page where the darkest and lightest colours meet, but the colours become the same towards the edges. The divide here doesn't exist, so this is a way to divide two sections and keep them visually connected at the same time.
You'll have to play around with the gradient colours to make sure the divide in the centre is visible, but the colours at the edges blend together.