site/_src/_assets/styles/bigchain/_header.scss

.header {
    position: relative;

    // background
    background: url('../img/photo1.jpg') no-repeat center bottom;
    background-size: cover;

    // color overlay
    &:before {
        content: "";
        width: 100%;
        height: 100%;
        position: absolute;
        left: 0;
        top: 0;
        bottom: 0;
        right: 0;
        background: linear-gradient(to top left, $brand-main-blue 0%, $brand-main-blue-dark 100%);
        opacity: .7;
        z-index: 0;
    }
}

.header__title {
    position: relative;
    z-index: 1;
    color: #fff;
    text-align: center;
    margin: 0;
    padding: ($spacer * 4) 0;
}