Working:

#C4C6BF

#C4C6BB;

red;

rgb(255,255,55,.5);

rgba(255, 0, 0, 0.5);

hsl(0deg, 100%, 50%);

hwb(12 50% 0%);

#C4C6BF;

cmyk(100%,50%,50%,50%);

hsva(360, 100%, 100%, 70%);

purple

This is a heading with a color code: #C4C6BF;

This is a paragraph with a #C4C6BB; color code inside. This is another paragraph with a red color code inside.

This is a nested paragraph with a rgb(255,255,55,.5); color code inside.

This is a nested paragraph with a rgba(255, 0, 0, 0.5); color code inside.

This is a paragraph with a CMYK color code: cmyk(100%, 50%, 50%, 50%);

This is a paragraph with an HSVA color code: hsva(360, 100%, 100%, 70%);.

This is a paragraph with an HSL color code: hsl(240, 100%, 50%);

This is a paragraph with an HWB color code: hwb(180 50% 0%);

      This is a code window with a #C4C6BF; color code.
    

Excluded elements