css3渐变色输入框

<input class="aaa" value="" type="text">

.aaa {
    width:400px;
    height:50px;
    font-size:24px;
    font-family:'楷体';
    box-sizing:border-box;
    border:3px solid transparent;
    background-clip:padding-box,border-box;
    background-origin:padding-box,border-box;
    background-image:linear-gradient(90deg,#000,#ff00ff),linear-gradient(90deg,#000,red);
}