Modification of map display in Open Street Map

There is a problem in displaying OpenStreetMap information. It is also that the numbers that show the height of the contour lines are not well defined!
In my opinion, their color and size should be changed.

Contour lines are not part of OpenStreetMap, and have been added by whomever has created that particular map based on some external data source for contour lines.

How did you create this screenshot, and which map have you selected? Those would be your primary contacts for your concern.