Ok, I think I figured out the issue. It's not that there's a tiny pixel, but in looking at the HTML source, it looks like the divs containing the buttons are being re-drawn frequently. This means that actually clicking the button is a crap-shoot because you might click when it's not on the screen, but looks like it is.
You're welcome! I also saw some weird behavior today when I re-opened the game in a new browser tab where the charged quarks were not immediately available even though I had been purchasing upgrades for them last night.
