This feature may not usually required, but today, April 4, 2020, to mourn the sacrifice of the heroes in the fight against SARS, many sites have turned into black and white, take a look at how today's technology to achieve
Css3 filter with the property, can be realized in some simple image filter effects ps:
Gray: grayscale
Blur: blur
Contrast: contrast
Hue rotation: hue-rotate
Shadow: drop-shadow
Achieve pure black and white, just to set style html filter: grayscale (100%);
Can be achieved using the hue-rotate animation gradient colors
drop-shadow shadows can achieve irregular shapes, different from box-shadow
Precautions: filter attribute compatibility issues, ie is not supported