It’s not HTML you’re after really. It’s the 16 bit (0-255) red, green, blue values which can produce 2563—or 16,777,216—colors via CSS. Zero is off, 255 is all the way on. So black is 0, 0, 0 and white is 255, 255, 255.
To use these in HTML, you need to use CSS. Inline example: <b style=“color:rgb(100,150,100)”>a nice green</b>.
We leave it as an assignment to reader to determine the color 196, 196, 196 will produce.
Since we’re on it, here is a command line Perl utitity to turn the rgb into hex.