fixed bug with screens with devicePixelRatio!=1
fixed bug with screens with devicePixelRatio!=1

janelia-flyem/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer