边框渐变

border: 1px solid;
border-image: -webkit-linear-gradient(90deg,#6772FF, #51E2F7) 5 10;
border-image: -moz-linear-gradient(90deg,#6772FF, #51E2F7) 5 10;
border-image: linear-gradient(90deg,#6772FF, #51E2F7) 5 10;