red,
orange,
yellow,
green,
blue,
purple, etc.
#ff0000,
#ff8000,
#ffff00,
#00ff00,
#0000ff,
#800080, etc.
rgb(255, 0, 0),
rgb(255, 128, 0),
rgb(255, 255, 0),
rgb(0, 255, 0),
rgb(0, 0, 255),
rgb(128, 0, 128), etc.
url('https://example.com/image.jpg')
linear-gradient(180deg, red, orange)
linear-gradient(180deg, #ff0000, #ff8000)
linear-gradient(180deg, rgb(255, 0, 0), rgb(255, 128, 0))
radial-gradient(red, orange)
radial-gradient(#ff0000, #ff8000)
radial-gradient(rgb(255, 0, 0), rgb(255, 128, 0))
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