That Divi built page is using background images for each of the sections. Which is not a nice way to do it. Simplest way i reckon, add this CSS:
.bottom-divider {
background: linear-gradient(175deg, rgba(255,255,255,0) 80%, rgba(244,225,4,1) 80%);
}
.top-divider {
background: linear-gradient(355deg, rgba(255,255,255,0) 80%, rgba(244,225,4,1) 80%);
}
Now you have three sections:
Section 1 has the bottom-divider
class
Section 2 has a solid color background to match divider colors
Section 3 has the top-divider
class