.colorful {
/* -webkit-mask-image: linear-gradient(to right, red, orange, yellow, green, cyan, blue, purple); */
background-image: linear-gradient(to right, red, orange, yellow, green, yellow, orange, red, orange, yellow, green, yellow, orange, red);
-webkit-background-clip: text;
-webkit-text-fill-color: transparent;
-webkit-background-size: 200% 100%;
animation: bgp 5s infinite linear;
}

@keyframes bgp{
0% {
background-position: 0 0;
}
100% {
background-position: -100% 0;
}
}

讓文字發出炫酷的光效果