使用场景
设置图片元素与父容器背景（黄色）进行混合，图片会变暗：
mix-blend-mode 具有哪些属性：
mix-blend-mode: normal;
mix-blend-mode: multiply;
mix-blend-mode: screen;
mix-blend-mode: overlay;
mix-blend-mode: darken;
mix-blend-mode: lighten;
mix-blend-mode: color-dodge
mix-blend-mode: color-burn;
mix-blend-mode: hard-light;
mix-blend-mode: soft-light;
mix-blend-mode: difference;
mix-blend-mode: exclusion;
mix-blend-mode: hue;
mix-blend-mode: saturation;
mix-blend-mode: color;
mix-blend-mode: luminosity;
使用场景：全站点统一修改，非常方便！
例如某个明星过世：所有图片会变成灰色：
正常情况下：
WX20211125-162503@2x.png
过世当天展示效果：
WX20211125-162611@2x.png
