Related to this, alpha channels can be very useful in writing a single colour that appears as different colours against known dark and light colours. For exampl

Related to this, alpha channels can be very useful in writing a single colour that appears as different colours against known dark and light colours. For example, see the mention of #8888 in https://chrismorgan.info/blog/dark-theme-implementation/ https://chrismorgan.info/blog/dark-theme-implementation/, where that #8888 becomes effectively #bfbfbf against white, and #484848 against black.