div {
position: relative;
width: 80%;
height: 200px;
margin: auto;
background: linear-gradient(to bottom, yellow, orange);
}
div::before,
div::after {
content: "";
position: absolute;
bottom: 0;
width: 50%;
height: 50px;
}
div::before {
background: linear-gradient(to right top, #00f 49.3%, transparent 50.8%);
}
div::after {
right: 0;
background: linear-gradient(to left top, #00f 49.3%, transparent 50.8%);
}