#page-header {
    position: relative;
    background-color: transparent !important;
    transition: all 0.2s ease !important;
}

#page-header::before{
    /* 创建覆盖层：模糊效果 */
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 80%;
    height: 80%;
    background-image: url(/images/Banner.png);
    background-size: cover;
    background-position: center;
    transition: all 0.2s ease !important;
    z-index: -2;
}


#page-header::after { 
    /* 创建覆盖层：纯色滤镜 */
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(42, 121, 212, 0.3);
    z-index: -1;
    transition: background-color 0.2s ease;
}


#page-header.blur-banner::after {
    /* 在page-header处于“blur-banner”下，改变after的属性（变不透明） */
    background-color: rgba(88, 146, 228, 0.3);
}

#page-header.blur-banner::before{
    /* 在page-header处于“blur-banner”下，改变before的属性（应用滤镜）*/
    filter: blur(20px);
}