目前支持的浏览器有Safari 9 +, iOS 9 +

@supports (-webkit-backdrop-filter: none) or (backdrop-filter: none) {
    .header {
        background: rgba(255, 255, 255, .6);
        -webkit-backdrop-filter: brightness(1.5) blur(4px);
        backdrop-filter: brightness(1.5) blur(4px);
    }
}
backdrop-filter

毛玻璃效果