Rectangular Tetradic Palette Generator

Rectangular Tetradic Palette Generator

Builds a fixed rectangular tetrad at HSL offsets 0,60,180,240 degrees. It is two complementary pairs, not the equally spaced square palette. Default #3B82F6 is editable through HEX/RGB/HSV/HSL panels; the rectangle spacing is fixed and there is no angle selector.

Verified example: #FF0000 produces red #FF0000, yellow #FFFF00, cyan #00FFFF, blue #0000FF. Offsets zero preserve the exact base; remaining swatches use the base hue, saturation and lightness rounded to whole HSL units before applying the offsets. Rounded conversion can differ slightly from other palette generators.

Calculate explicitly to display four editable panels and their text. Manually editing a result changes only that color, not the rest of the tetrad. Clear restores default base and empties results. Use the four-color palette as design candidates, not as a guaranteed accessible combination; consider a dominant base and test chosen text/background pairs separately.

Runs in the browser with no photo upload or server calculation. No automatic contrast score, color-blind simulation or palette-file format selector is supplied. Mobile users choose the base and calculate then inspect all four swatches. HEX outputs are independent of local date and CSV formats.