Additional Color Gradients in Main Table

[JLindemann42]

Is your feature request related to a problem? Please describe. When previewing for example melting points in the main table, all element button backgrounds are the same color. To more easily see differences between elements more color gradients like the one for electronegativity should be added.

Describe the solution you'd like A similar implementation as the one for electronegativity. Further development in TableExtension.kt should be the easiest and beat solution.

Additional context Thanks to William Courchesne for submitting this idea!