• HTML
• CSS

HTML

<h1 data-text="Text">Text</h1>

CSS

body
{
    margin:0;
    padding:0;
    font-family:sans-serif;
    background:#262626;
}
h1
{
    position:absolute;
    top:50%;
    left:50%;
    transform:translate(-50%,-50%);
    margin:0;
    padding:0;
    font-size:10em;
    text-transform:uppercase;
    color:#fff;
    -webkit-text-stroke:2px #fff;
}
h1:before
{
    content:attr(data-text);
    position:absolute;
    background:linear-gradient(90deg,#d630f2,#ff002f,#e4ff00,#d630f2);
    background-size:300%;
    overflow:hidden;
    transition:width 2s;
    animation:animate 5s linear infinite;
    width:0;
    -webkit-background-clip:text;
    -webkit-text-fill-color:transparent;
}
h1:hover:before
{
    width:100%;
}
@keyframes animate
{
    0%
    {
        background-position:0 0;
    }
    100%
    {
        background-position:300% 0;
    }
}