symply clever által készített css kód..
Azok számára, akik használni akarják

[url]echo "
.rainbow-text {
animation-duration: 3.115s;
}
/*fb8532*--000000*/
/*2188ff--2846F0*/
/*ffd33d--1DB30F*/
.rainbow-text {
background: linear-gradient(43.13deg,#ffd33d 0,#000000 90%,#ea4a5a 90%,#8a63d2 90%,#2846F0 90%,#34d058 90%,#1DB30F 100%);
background-size: auto;
background-clip: border-box;
background-clip: text;
display: inline-block;
color: transparent;
text-fill-color: transparent;
-webkit-background-clip: text;
-webkit-text-fill-color: transparent;
animation: shine 6.28s alternate infinite;
animation-duration: 6.28s;
background-size: 300%;
font-size: 30px;
}

@keyframes shine {
0% {
background-position:200% center
}
62.8% {
background-position:100% center
}
100% {
background-position:200% center
}
}

";
/******************************END*********************/

echo "<div class='rainbow-text'><strong>Your text</strong></div>";
[/url]