Wrapping to a fixed width such that each line is the same length in characters

I'm attempting to wrap this long <pre> so that it forms a rectangle (rather than having the "jagged" endings I'm getting). I've set white-space to pre-wrap and word-break to break-all like other StackOverflow posts have suggested, but it seems like the browser is still applying some heuristics on where to break the line.

I cannot break the <pre> into rows a-priori because both the length of the content, as well as the width of the <pre> may be dynamic.

pre {
  width: 300px;
  white-space: pre-wrap;
  word-break: break-all;
}

<pre>ER..............................3......|..f1.f1.fSfQ.W....R..|.........K...R.A..U1.0....r...U.u....t.f.....B....1.ZQ....[...@P..?Q..SRP..|...f....D.....f@.....f.&gt;@|..xpu....{.D|.....isolinux.bin missing or corrupt...f`f1.f...{f...{fRfP.Sj.j...f.6.{.........6.{....A......{...d.fa....Operating system load error...^....&gt;b.....&lt;.u........................</pre>

What I have:

What I want to achieve: