:root {
--inverted-corners-background: #52525b;
--inverted-corners-size: 2rem;
}
.inverted-corners {
background-color: var(--inverted-corners-background);
position: relative;
}
.inverted-corners::before {
content: '';
bottom: calc(-2 * var(--inverted-corners-size));
left: 0;
position: absolute;
height: calc(2 * var(--inverted-corners-size));
width: var(--inverted-corners-size);
background-color: transparent;
border-top-left-radius: var(--inverted-corners-size);
box-shadow: var(--inverted-corners-background) 0px calc(-1 * var(--inverted-corners-size)) 0px
0px;
}