.a1{
    position: relative;
    padding: 5px 50px;
    text-decoration: none;
    color: #fff;
    font-size: 2em;
    text-transform: uppercase;
    font-family: sans-serif;
    letter-spacing: 4px;
    overflow: hidden;
    background: rgba(255,255,255,.1);
    box-shadow: 0 5px 5px rgba(0,0,0.2);
    background: linear-gradient(-30deg, #86bc42 0%,#86bc42 50%,#3598DB 50%,#ffffff 100% );
    display: flex;
    justify-content: center;
    align-content: center;
    align-items: center;
}
.a1:before{
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 50%;
    height: 100%;
    background: rgba(255,255,255,.1);
}
.a1:after{
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg,transparent,rgba(255,255,255,.4),transparent);
    transition: 0.5s;
    transition-delay: 0.5s;
}
.a1:hover:after{
    left: 100%;
}
.a1 span{
    position: absolute;
    display: block;
    transition: 0.5s ease;
}
.a1 span:nth-child(1)
{
    top: 0;
    left: 0;
    width: 0;
    height: 1px;
    background: #fff;
}
.a1:hover span:nth-child(1)
{
    width: 100%;
    transform: translateX(100%);
}
.a1 span:nth-child(3)
{
    bottom: 0;
    right: 0;
    width: 0;
    height: 1px;
    background: #fff;
}
.a1:hover span:nth-child(3)
{
    width: 100%;
    transform: translateX(-100%);
}
.a1 span:nth-child(2)
{
    top: 0;
    left: 0;
    width: 1px;
    height: 0;
    background: #fff;
}
.a1:hover span:nth-child(2)
{
    height: 100%;
    transform: translateY(100%);
}
.a1 span:nth-child(4)
{
    bottom: 0;
    right: 0;
    width: 1px;
    height: 0;
    background: #fff;
}
.a1:hover span:nth-child(4)
{
    height: 100%;
    transform: translateY(-100%);
}