body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    font-family: "Zilla Slab", serif;
    background-color: #060c21;
}

.box {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    width: 300px;
    height: 400px;
    padding: 25px;
    color: #fff;
    background-color: #060c21;
    box-sizing: border-box;
}

.box:before {
    content: "";
    position: absolute;
    top: -2px;
    right: -2px;
    bottom: -2px;
    left: -2px;
    z-index: -1;
}

.box:after {
    content: "";
    position: absolute;
    top: -2px;
    right: -2px;
    bottom: -2px;
    left: -2px;
    z-index: -2;
    filter: blur(40px);
}

.box:before,
.box:after {
    background: linear-gradient(135deg, #89ff00, #060c21, #00bcd4);
}