html
{
    height: 100%;
}
body
{
    color: #fff;
    margin: 0;
    padding: 0;
    font-family: sans-serif;
    background: linear-gradient(#000000, #434343);
}
.login-box
{
    position: absolute;
    top: 50%;
    left: 50%;
    width: 400px;
    padding: 40px;
    transform: translate(-50%, -50%);
    background-color: rgba(0, 0, 0, .5);
    box-sizing: border-box;
    box-shadow: 0 15px 25px rgba(0, 0, 0, .6);
    border-radius: 10px;
}
.loagin-box h2
{
    margin: 0 0 30px;
    padding: 0;
    color: #fff;
    text-align: center;
}
.login-box .user-box
{
    position: relative;
}
.login-box .user-box input
{
    width: 100%;
    padding: 10px 0;
    font-size: 16px;
    color: #fff;
    margin-bottom: 30px;
    border: none;
    background: transparent;
    outline: none;
    border-bottom: 1px solid #fff;
    background: transparent;
}
.login-box .user-box label
{
    position: absolute;
    top: 0;
    left: 0;
    padding: 10px 0;
    font-size: 16px;
    color: #fff;    
    pointer-events: none;
    transition: .5s;
}
.login-box .user-box input:focus ~ label,
.login-box .user-box input:valid ~ label
{
    top: -20px;
    left: 0;
    color: #ff0043;
    font-size: 12px;
}
.login-box form a
{
    position: relative;
    display: inline-block;
    padding: 10px 20px;
    color: #ff0043;
    text-decoration: 16px;
    text-transform: uppercase;
    overflow: hidden;
    transition: .5s;
    margin-top: 40px;
    letter-spacing: 4px;
}
.login-box a:hover
{
    background: #ff0043;
    color: #fff;
    border-radius: 5px;
    box-shadow: 0 0 5px #ff0043,
                0 0 25px #ff0043,
                0 0 50px #ff0043,
                0 0 100px #ff0043;
}
.login-box a span
{
    position: absolute;
    display: block;
}
.login-box a span:nth-child(1)
{
    top: 0;
    left: -100%;
    width: 100%;
    height: 2px;
    background: linear-gradient(90deg, transparent, #ff0043);
    animation: btn-anim1 1s linear infinite;
}
@keyframes btn-anim1
{
    0%
    {
        left: -100%;
    }
    50%,100%
    {
        left: 100%;
    }
}
.login-box a span:nth-child(2)
{
    top: -100%;
    right: 0;
    width: 2px;
    height: 100%;
    background: linear-gradient(180deg, transparent, #ff0043);
    animation: btn-anim2 1s linear infinite;
    animation-delay: .25s;
}
@keyframes btn-anim2
{
    0%
    {
        top: -100%;
    }
    50%,100%
    {
        top: 100%;
    }
}
.login-box a span:nth-child(3)
{
    bottom: 0;
    right: -100%;
    width: 100%;
    height: 2px;
    background: linear-gradient(270deg, transparent, #ff0043);
    animation: btn-anim3 1s linear infinite;
    animation-delay: .5s;
}
@keyframes btn-anim3
{
    0%
    {
        right: -100%;
    }
    50%,100%
    {
        right: 100%;
    }
}
.login-box a span:nth-child(4)
{
    bottom: 0;
    left: 0;
    width: 2px;
    height: 100%;
    background: linear-gradient(360deg, transparent, #ff0043);
    animation: btn-anim4 1s linear infinite;
    animation-delay: .75s;
}
@keyframes btn-anim4
{
    0%
    {
        bottom: -100%;
    }
    50%,100%
    {
        bottom: 100%;
    }
}