Update file browser css
Update file browser css

jupyter/jupyter-js-plugins,blink1073/jupyter-js-plugins,blink1073/jupyter-js-plugins,jupyter/jupyter-js-plugins,blink1073/jupyter-js-plugins,blink1073/jupyter-js-plugins,blink1073/jupyter-js-plugins,jupyter/jupyter-js-plugins,jupyter/jupyter-js-plugins,jupyter/jupyter-js-plugins