.container {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 90%;
    max-width: 1200px;
    text-align: center;
}
.container .btn {
    display: inline-block;
    width: 70px;
    height: 70px;
    background-color: rgb(0, 0, 0);
    box-shadow: 0 5px 15px -5px rgb(23, 236, 16);
    margin: 10px;
    border-radius: 30%;
    overflow: hidden;
    position: relative;
    color: #1cab15;
}
.container .btn i {
    position: relative;
    z-index: 4;
    line-height: 70px;
    font-size: 26px;
    transition: 0.3s ease-in-out;
}
.container .btn::before {
    content: "";
    position: absolute;
    width: 120%;
    height: 120%;
    background: linear-gradient(#2ae555, #14bd08);
    transform: rotate(45deg);
    left: -110%;
    top: 130%;
}
.container .btn:hover i {
    color: rgb(0, 0, 0);
    transform: scale(1.3);
}
.container .btn:hover::before {
    animation: onHover 0.7s 1;
    left: -10%;
    top: -10%;
}
@keyframes onHover {
    0% {
        left: -110%;
        top: 90%;
    }
    50% {
        left: 10%;
        top: -30%;
    }
    100% {
        top: -10%;
        left: -10%;
    }
}