[OSM-newbies] mgkmap colors rendering to Garmin MapSource

[swanilli]

Can anyone enlighten me on the way in which colors are handled between
OSM to MapSource via mgkmap?

For example, if I customize mgkmap styles for polygons thus:

   leisure=common [0x17 resolution 20]

appears as solid pale green in MapSource and 0x50 as horizontal brown
lines, 0x4e as vertical red lines and so on. All very random and time
consuming.

My problem is that I want to show beaches as solid yellow but have
been reduced to

  natural=beach [0x01 resolution 20]

which renders as a very pale blue.

I assume there is some key to this code. I understand the "resolution
20" bit but the colors escape me.