Spectrum background

Spectrum background

overlay three gradients to make a background with nearly the full spectrum of colors that can be displayed on a monitor.
https://blog.logrocket.com/advanced-effects-with-css-background-blend-modes-4b750198522a

.spectrum-background {
    background:
        linear-gradient(red, transparent),
        linear-gradient(to top left, lime, transparent),
        linear-gradient(to top right, blue, transparent);
    background-blend-mode: screen;
}