I think it is just the smaller resolution width. I expect the code box is fixed width and doesn't adjust to display resolution.
This was really a test to see how many lines of code were allowed before the vertical scroll bar kicks in. I find it frustrating, often near impossible, to understand code in a small vertical window, and likewise anything longer than a screen page, and expect 'noobs' to have even greater problems. The code can be cut and pasted to notepad but that's just unwanted faffing about.
I've gone back to indenting code with leading minuses so the entire code is visible in one glance. It loses the benefits of being mono-spaced, especially with comments, and adds the need to delete that crud after cut and paste, but think the advantages outweigh the downsides.
Added : On the matter of vertical resolution, I can see 11 lines in the scroll box, how many do you see ?
Added : Yes it's a fixed width/height scroll box, form View Source ...
Code:
<pre class="alt2" dir="ltr" style="
margin: 0px;
padding: 6px;
border: 1px inset;
width: 640px; <=== HERE
height: 178px; <=== HERE
text-align: left;
overflow: auto">1