The reason why HTML think “chucknorris” is a color because it starts with c, and the browser reads it into a hexadecimal value.
We know that A, B, C, D, E, and F are characters in hexadecimal.
So the browser converts chucknorris to a hexadecimal value, C00C00000000. Then that hexadecimal value is converted to RGB format (after dividing by 3).
C00C00000000 => R:C00C, G:0000, B:0000
For indicating the color the browser needs only two digits to indicate the colour:-
R:C00C, G:0000, B:0000 => R:C0, G:00, B:00 => C00000
At last, it shows bgcolor = C00000 in the web browser.