I am fairly new to python and have no html experience. The question has been asked and either not answered at all or not answered in enough detail for me to set the default
Using Jupyterthemes, one can easily change look of notebook.
pip install jupyterthemes jt -fs 15
By default code font size is set to 11 . Trying above will change font size. It can be reset using.
jt -r
This will reset all jupyter theme changes to default.