html element:html::after element.background: linear-gradient(...); on the html selector.background-color: oklch(...) that matches the color of the top triangle. If not, I could see glimpses of a white background on top of the page and at bottom of page.background-color , I only see the background: linear-gradient(...), which makes it look funny on the top, but great at the bottom.background vs background-image, at least on the html selector? 