.feature-block .icon-box {
    position: relative;
    display: inline-block;
    margin-bottom: 1rem;
}

.feature-block .icon-box img {
    transition: opacity 0.3s ease;
}

.feature-block .icon-box .hover-icon {
    position: absolute;
    top: 0;
    left: 0;
    opacity: 0;
}

.feature-block:hover .icon-box .normal-icon {
    opacity: 0;
}

.feature-block:hover .icon-box .hover-icon {
    opacity: 1;
}