In order to achieve a header that changes from transparent to a solid header, you can do that by following this tutorial:You need to create a solid header that is sticky. Make sure you set the sticky to "Show on Sticky", so it will only show when it is sticky.Below that solid header, you need to create a transparent header.That's it By doing so, you will have a header that transitions from a transparent to a solid header on scrolling.
How to transition from a transparent to a solid header on scrolling?
How to transition from a transparent to a solid header on scrolling?