.rainbow {
    background-image: -webkit-linear-gradient(left, #7a19a9, #c469f0, #7a19a9);
    background-image: -moz-linear-gradient(left, #7a19a9, #c469f0, #7a19a9);
    background-image: -o-linear-gradient(left, #7a19a9, #c469f0, #7a19a9);
    background-image: -ms-linear-gradient(left, #7a19a9, #c469f0, #7a19a9);
    background-image: -khtml-linear-gradient(left, #7a19a9, #c469f0, #7a19a9);
    background-image: linear-gradient(left, #ff6698, #7a19a9, #7a19a9);
    -moz-animation: rainbow 4s forwards linear infinite;
    -webkit-animation: rainbow 4s forwards linear infinite;
    -o-animation: rainbow 4s forwards linear infinite;
    -khtml-animation: rainbow 4s forwards linear infinite;
    -ms-animation: rainbow 4s forwards linear infinite;
    -lynx-animation: rainbow 4s forwards linear infinite;
    animation: rainbow 4s forwards linear infinite;
    background-size: 50% auto;
}

@-moz-keyframes rainbow {
    from {
        background-position: top left;
    }

    to {
        background-position: top right;
    }
}

@-webkit-keyframes rainbow {
    from {
        background-position: top left;
    }

    to {
        background-position: top right;
    }
}

@-o-keyframes rainbow {
    from {
        background-position: top left;
    }

    to {
        background-position: top right;
    }
}

@-ms-keyframes rainbow {
    from {
        background-position: top left;
    }

    to {
        background-position: top right;
    }
}

@-khtml-keyframes rainbow {
    from {
        background-position: top left;
    }

    to {
        background-position: top right;
    }
}

@keyframes rainbow {
    from {
        background-position: top left;
    }

    to {
        background-position: top right;
    }
}