For screen presentations, I found the original font-size to be too small. Therefore, adjusting the font size permanently would be nice to have.
You can do so by adding a custom Cascading Style Sheet (CSS) to your Jupyter configuration directory (usually in $HOME/.jupyter/). First you add a subdirectory called “custom” to your Jupyter configuration directory ($HOME/.jupyter/custom)
Next you create the style sheet $HOME/.jupyter/custom/custom.css:
#notebook-container div,
#notebook-container table {
font-size:12.5pt !important;
}
This is likely not the ultimate CSS if you want to fine-tune your Jupyter notebook style, but it does the job for our purpose to resize most of the text.