How To Change Edge Color of Strip?

Question:
How do I change the white section of this wavey-shaped strip to transparent?

Product:
Wix Editor

What are you trying to achieve:
I want the wavey yellow lines above to flow behind the strip image, and not have a break in color (I want the white parts removed)

What have you already tried:
When I change background color, or change the background image, or make it transparent, the white edges above the wavey lines remain - it only changes what is within.

Additional information:
Thanks for any help!