body {
    background: red;  /* fallback for old browsers */
    background: -webkit-linear-gradient(to right, red, yellow);  /* Chrome 10-25, Safari 5.1-6 */
    background: linear-gradient(to right, red, yellow); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
}

u {
    background: purple;
    color: white !important;
}