CSS는 배경 동적 그라데이션 효과를 실현합니다.

*{
    margin: 0;
    padding: 0;
}

body{
    height: 100vh;
    width: 100%;
    overflow: hidden;
    background-image: linear-gradient(125deg,#F44336,#E91E63,#9C27B0,#3F51B5,#2196F3);
    background-size: 400%;
    font-family: "montserrat";
    animation: bganimation 15s infinite;
}

.text{
    color: #fff;
    font-size: 22px;
    text-align: center;
    margin: 350px 0;
    /* text-transform: uppercase; */
}

@keyframes bganimation{
    0%{
        background-position: 0% 50%;
    }
    50%{
        background-position: 100% 50%;
    }
    100%{
        background-position: 0% 50%;
    }
}