視差動畫css

   color: rgba(255, 255, 255, 0.75);
    background-attachment: fixed;
    background-image: linear-gradient(rgba(96, 96, 96, 0.25), rgba(0, 0, 0, 0.82)), url(../Img/last_letter_img.jpg);
    background-position: bottom;
    background-repeat: no-repeat;
    background-size: cover;
    text-align: center;
    z-index: 1;
    padding: 50px 0px;