Hitting the "Choose" button without changing the select fields from dashes generates random strings for the Menu number and Color designation. However, although the code for both is very similar, there seems to be more letters (corresponding to ten to fifteen decimal) in the Menu. Clicking the page title also refrehes the number and color. The drop-downs will select their number and color.
There also seems to be an excess of palindromes in the Color(s). Also, a preponderence of shades of green. I suspect a less-than-perfect randomness in character picks. The outside of the block is the code indicated; the interior is the reverse. The larger (usually) three or (sometimes) six digit string up above in each block is the hex code for the color rendered. Selecting exits the site.
Right to left the colors run red green blue. Intensity is from 00 (zeros, equals empty) to "FF" (saturated). Thus, #000000 is black and #FFFFFF is white. A three digit number is a sort of shorthand for doubled digits. RGBA is the same expressed digitally plus a "depth" level from 0 to 1. There are also several other ways to express colors on the web. NB: HSL(175, 94%, 77%) HSL(175, 94%, 77%)
Units of measurement seem to render differently around the canvas. This is not generally considered possible. Sometimes the page fails to render. Just ckick a number then select somthing from the dropdown. The page will be back.
Hitting the "Choose" button without changing the select fields from dashes generates random strings for the Menu number and Color designation. However, although the code for both is very similar, there seems to be more letters (corresponding to ten to fifteen decimal) in the Menu.