Fixing max-height bug on Firefox.
Fixing max-height bug on Firefox.

jupyter/jupyterlab,jupyter/jupyterlab,TypeFox/jupyterlab,charnpreetsingh185/jupyterlab,eskirk/jupyterlab,jupyter/jupyterlab,eskirk/jupyterlab,charnpreetsingh185/jupyterlab,charnpreetsingh185/jupyterlab,TypeFox/jupyterlab,eskirk/jupyterlab,eskirk/jupyterlab,TypeFox/jupyterlab,eskirk/jupyterlab,charnpreetsingh185/jupyterlab,TypeFox/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab,TypeFox/jupyterlab,charnpreetsingh185/jupyterlab