.tvbbut {
    background-color: #0cf;
    display: inline-block;
    padding: .75rem 1.25rem;
    border-radius: 10rem;
    color: #555;
    text-transform: uppercase;
    font-size: 1rem;
    letter-spacing: .15rem;
    transition: all .3s;
    position: relative;
    overflow: hidden;
    z-index: 1;
    &:after {
        content: '';
        position: absolute;
        bottom: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: #0cf;
        border-radius: 10rem;
        z-index: -2;
    }
    &:before {
        content: '';
        position: absolute;
        bottom: 0;
        left: 0;
        width: 0%;
        height: 100%;
        background-color: darken(#0cf 15%);
        transition: all .3s;
        border-radius: 10rem;
        z-index: -1;
    }
    &:hover {
        color: #fff;
        &:before {
            width: 100%;
        }
    }
}