Every word in it is absolutely positioned; e.g.
Code:
<span id="_idTextSpan4945" class="CharOverride-19" style="position:absolute;top:6584.25px;left:1986.07px;letter-spacing:-0.13px;">unprecedented </span>
So I don't think it's the size but all of that html stuff. Like DNSB said, another approach would more likely be fruitful. Maybe figure out a way to strip out the spans around each word, and then start over reformatting it.
I opened it in Sigil and its previewer displays it nicely. Likewise with Adobe Digital Editions. And Calibre's viewer. But the font size is fixed and small so it's hard to read.
I'm tempted to load it onto my kobo and see if it crashes it.