Full spectrum
linear-gradient(90deg, #FF0000, #FF8C00, #FFD700, #00C853, #00D9F5, #0A84FF, #8F00FF)
In the color library: red #FF0000, gold #FFD700
A rainbow gradient runs the full spectrum in one sweep, red through violet, the way a prism spreads white light. It is the loudest background there is, which is exactly why the working versions below include softer ones: the full-strength spectrum is for moments, not for pages of text.
The full spectrum here uses seven stops at even spacing, so no single hue dominates the run. The pastel and muted versions keep the same hue order and pull saturation down, which preserves the rainbow reading while letting content sit on top. Horizontal sweeps read as banners; set the angle to 180 for a top to bottom background.
linear-gradient(90deg, #FF0000, #FF8C00, #FFD700, #00C853, #00D9F5, #0A84FF, #8F00FF)
In the color library: red #FF0000, gold #FFD700
linear-gradient(90deg, #FFB3BA, #FFDFBA, #FFFFBA, #BAFFC9, #BAE1FF, #E5D4FF)
The same hue order with the saturation pulled down, so dark text stays readable along the whole run.
linear-gradient(90deg, #800000, #B34700, #8B6914, #0F5132, #0F52BA, #4B0082)
Every stop darkened toward its shade, for white text and darker interfaces.
In the color library: maroon #800000, indigo #4B0082
linear-gradient(135deg, #FF2965, #FCFF52, #00F5D4, #00A3FF, #FF00E5)