Home and dust on CSS style

2020/4/4 national day of mourning, the major Home turned gray, then how to achieve this effect?

Just add the following to the global CSS styles:

html,html *{
  filter:gray!important;
  filter:progid:DXImageTransform.Microsoft.BasicImage(grayScale=1);
  filter:grayscale(100%);
  -webkit-filter:grayscale(100%);
  -moz-filter:grayscale(100%);
  -ms-filter:grayscale(100%);
  -o-filter:grayscale(100%);
}