Hi Marc!
The angled objects at the top of the home page in the Wedge theme are CSS pseudo elements and their design can be altered with Custom CSS in your website Customizer.
You can target the element on the left with the body:before selector and the right one with body:after. The angled shapes of those elements are created using colored and transparent borders applied to the pseudo elements and if you want to change the color of both then you can use the border-top-color property. Here is an example snippet that you could use to adjust the color of those elements with a single rule:
body:before,
body:after {
border-top-color: rgba( 100 , 100 , 100 , 0.5 );
}
The first three numbers in that rule are RGB values (Red, Green, Blue) on a scale of 0 to 255, and the fourth one is the transparency value which uses a 0 to 1 scale.
I hope that this helps you make the design adjustments that you need and please let us know if you have any other questions for us!