I was delighted to view your inflation pages and appreciated the ease in which the rates were made clear, the various frankings to achieve the rates, (I am a big fan of Mi frankings from anywhere), the first day of stamp uses, the first day and last day of rates, the examples of only 3 or 4-days of valid single franking.
The patterned border is terribly distracting, and the gray borders distracting. Your covers have enough color tone to them to set them off a white page on their own. The gray inhibits this.
Should you be able to make one adjustment, in your 3 columns where you show 3 covers across showing the same rate with different stamps, it would be cleaner if you could insert just a single rate description across the top of all 3 covers instead of having to duplicate it atop each one.
I appreciated your larger images from the start and enlargement capability. Their resolution to me with casual interest was fine. Specialists would likely wisher clearer enlargements.
You stated from the onset that this is an online presentation, not a traditional philatelic exhibit. I have no trouble with what you have done given the restraints of your template other than the borders. It is far more ambitious than anything I have ever done.
Noe: On a pair of adjacent covers you have a technical error in a period of use, in that they are not the same by one day. You should spot it easily.
Thanks for taking the time to create this online reference, when completed it will be an easily used and valuable tool.