.page-header {
    background: linear-gradient(rgba(0, 0, 0, 0.5), rgba(169, 238, 255, 0.5)),
                url(../images/about/about-head.jpeg) no-repeat center center;
    background-size: cover;
    padding: 100px 50px; 
    position: relative;
    text-align: center;
}