网站水印效果

.page-header-warp {
    position: relative;
}

    .page-header-warp::after {
        content: "";
        z-index: 9;
        position: absolute;
        left: 0px;
        top: 0px;
        width: 100%;
        height: 100%;
        background-size: 300px;
        pointer-events: none;
        opacity: 0.3;
        background-repeat: repeat;
        background-image: url(../images/watermark.png);
    }