This is the code I ended up using. It stretches input & output cells to the left and right. Note that the input/output number indication will be gone:
from IPython.core.display import display, HTML
display(HTML("<style>.container { width:100% !important; }</style>"))
display(HTML("<style>.output_result { max-width:100% !important; }</style>"))
display(HTML("<style>.prompt { display:none !important; }</style>"))