gdal - Problem with contour lines thickness in bigger zoom levels

I'm a beginner user of GDAL tools. I'd like to rasterize contour lines into Tiff file (for example such region: N47E006), everything works for quite small zoom levels e.g. 10... but the problem is with bigger zoom levels... contour lines are very "pixelised" and for mountains black contour lines covers almost whole Tiff image. Is there a way to create thinner contour lines for bigger zoom levels e.g. 15-18?

I'm using this for generating contour lines (10m):

gdal_contour -a elev -i 10 input.tif contours.shp 

this for rasterization:

gdal_rasterize -b 1 -b 2 -b 3 -burn 0 -burn 0 -burn 0 -l contours contours.shp input.tif

and this for cutting into tiles:

gdal2tiles.py -z 15-18 -n -e -w openlayers input.tif out_dir