Not by webflow CSS editor. Use custom css code.
Add class to element X
(some div)
+
Match the CSS selector (
.test
in my example) + this code not so modular (You should change the color her)copy-paste (Embed html / or- in the head)
<style>
.test {
background:
linear-gradient(135deg, transparent 10px, #c00 0) top left,
linear-gradient(225deg, transparent 10px, #c00 0) top right,
linear-gradient(315deg, transparent 10px, #c00 0) bottom right,
linear-gradient(45deg, transparent 10px, #c00 0) bottom left;
background-size: 50% 50%;
background-repeat: no-repeat;
}
</style>