Hmm. That is odd, and not behavior I see in either Firefox or Chrome. I'm afraid my knowledge of CSS is insufficient to explain why that might be happening.
Widening my window reveals the hidden text. If I continue widening it, the .mainContentColumn will grow wider and the text within will reflow appropriately. But the .mainContentColumn will never shrink below 1349 pixels wide, and if the window is narrower than that, the text will still lay out in the wider space, which hides some of the text.
The "Shukriya" image is 1349 pixels [1] wide, which is probably setting the minimum width of the .mainContentColumn.
You have `width: 100vw` set on the .mainContentColumn, but I'm guessing the width of the picture is interfering with that. If I set `width: 100vw` on .text, text layout improves (though clipping is still present). If I set `width: 90vw`, text layout flows appropriately within the new narrower and entirely-visible box.
However, giving this different width to the .text paragraphs means that the tweet embeds and titles are no longer centered relative to the text (they're centered relative to the .mainContentColumn, but the text is narrower than that and left-justified).
[1] Some type of scaling appears to be going on; if I screenshot my browser, clipping the image, the screenshot is over 2000 pixels wide.
Thanks so much. You've really gone above and beyond with this comment. I very much appreciate it. I've made a couple tweaks that may resolve the issue. If you have a chance to take another look I'd love to know if it is or isn't working for you.
On this attempt, I got tweets in both quizzes in Chrome. (Still nothing in Firefox.) The Chrome tweets take a long time to load.
Bad text layout also occurs in Edge, which definitely doesn't have addons installed.