Current2020 SoM coloring (=use font colors) has issues.
As of 2021-01-23, an Emergency Edit has been made to make SoM-fontcolors into black all. W3C Contrast checking failed too often (5/18 existing combinations!)
A new presentation form (like icons not colors) is considered.
In PTG, hex color triplets are shown in lowercase: 3af8ee.
"Chemical categorisation" explicitly refers to the science. For example, the "2020 categorisation" scientifically re-introduced "Halogens" category. After this, the topic "Colors of categories" will follow.
Category names are not relevant. For example, former PTM Post-transition metals is in 2020: OM Other Metals. Does not effect color design.
Also, exact category memberlist not very important. Except maybe when checking for neigbours (bordering).