<div></div>
div {
    margin: 10px auto;
    width: 200px;
    height: 200px;
    background: #fc0;
}

@supports (background:-webkit-linear-gradient(0deg, yellow, red)) or (background:linear-gradient(90deg, yellow, red)){
    div {
        background:-webkit-linear-gradient(0deg, yellow, red);
        background:linear-gradient(90deg, yellow, red)
    }
}

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