/usr/lib/python2.7/dist-packages/IPython/frontend/html/notebook/static/css/ is in ipython-notebook 0.12.1+dfsg-0ubuntu1.
This file is owned by root:root, with mode 0o755.
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/usr/lib/python2.7/dist-packages/IPython/frontend/html/notebook/static/css/base.css
/usr/lib/python2.7/dist-packages/IPython/frontend/html/notebook/static/css/boilerplate.css
/usr/lib/python2.7/dist-packages/IPython/frontend/html/notebook/static/css/layout.css
/usr/lib/python2.7/dist-packages/IPython/frontend/html/notebook/static/css/notebook.css
/usr/lib/python2.7/dist-packages/IPython/frontend/html/notebook/static/css/projectdashboard.css
/usr/lib/python2.7/dist-packages/IPython/frontend/html/notebook/static/css/renderedhtml.css