Meaning of symbols in OpenHikingMap

Hello,

for hiking I started using OpenHikingMap. However I wonder what some of the symbols in this map mean and up to now I was unable to find a complete legend. Look at the map tile in this link

What is the meaning of the unfilled brown double line with intersections visible in the upper left side of the png? What do red lines and white lines stand for? Is there a legend somewhere, that explains the symbols?

Thanks a lot Rainer