这种很亮丽的颜色是怎么计算的?如果随便计算出来的肯定很丑的,像这种是通过什么规则计算出来的?

下面代码是百度代码,每次刷新都是新的,颜色应该是JS计算出来的,想知道是怎么计算的,或者说是什么规则?

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