I explored a bit with the debug tools.
The width is set as a style on the div with the .ace_content class, so you must force it with !important, for example. But it won’t help, as it changes only the viewport, not the wrapping.
Which is actually a hard wrapping, not a soft one. Ie. that’s not the browser setting the wrapping of lines at div border, but that’s Ace editor which cuts the lines on the fly, each line being a div (ace_line).
I guess that’s why there is the setting pointed out by dpoulton: it probably provides the information to the editor too, which uses it to measure the lines, or something like that.
