included examples with manual background color selection via inputs and automatic color of a plot based on its value.
let your rainbow dreams come true!! :D
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.