Although I can understand the desire to fit a decent amount of code into a block, I think the difference between the main body text and code is too great: the code was legible but pretty small from the back of a lecture theatre. Perhaps change to 0.9rem?
Related to this, when I came to delivering these slides I actually wanted the static code to have a consistent font-size with the above, so went for 0.9rem there too.
The code.css stylesheet has an entry
Although I can understand the desire to fit a decent amount of code into a block, I think the difference between the main body text and code is too great: the code was legible but pretty small from the back of a lecture theatre. Perhaps change to 0.9rem?