... and why is there an eCart display on my checkout page? ... and why is there an image placeholder on it when I removed it from my cart page? ... and what's with the latin at the bottom of the page? Why can I not edit this on page? Where have you hidden it?
You keep forgetting the KISS principle. Keep it Simple S-----d. Your code is bloating badly and the usability is going downhill. There is precious little here that was worth the upgrade. In fact, there is NOTHING here that was worth the upgrade. There is NO functionality at all that I did not have in eCart 5 with the exception of the ability to hide a few items dynamically based on screen size, which I over-rode in the GUI.
On that note, why would you default to hiding the Update and Clear Cart buttons on a small screen and not give the ability to over-ride the choice?