here's a little colour picker i made
you can drag your mouse left and right on the labels for the numbers to go up and down
you can put whatever you want in the CSS box as long as it's a css color ("#123456", "rebeccapurple", "rgb(255, 255, 255)", ...)
don't look at the code
limitations and clamping
the swatch is coloured with an RGB hex value, so colours outside of the sRGB gamut won't look correct.
color spaces in the "sRGB" section have their inputs clamped to not produce values outside of the sRGB gamut.
color spaces in other sections have their lightnesses clamped to not produce a white with Y > 1 in CIE 1931, and cylindrical models have their hue angles clamped to 0-360°.
other values are unclamped, so there's no guarantee a colour isn't impossible. if necessary, check if the xyY values make sense yourself.
"clamp chroma" produces the swatch color by reducing the chromaticity of the color (in your selected model or LCh if your model has no chromaticity axis) until it falls into sRGB gamut. "clamp RGB" just limits the RGB values to 0-255 directly.