Global Header options
Global header options (that apply to all pages) can be found in Theme tools > Theme options > Header
You can choose any color in the background picker but what about transparent header?
Well simply input a rgba code in the color picker
For example this is a transparent color
You can convert any hex color to rgba and make it transparent, by using the service below
Page specific header options
Page specific header options can be found by editing the page with elementor, going to Elementor menu > Page settings > Customize header. There’s a built in transparency feature in Elementor which makes the process very easy. Watch the video below to learn how