So it's doing like you said, the default behavior of wrapping on white space.

I remember I ran into this issue on the built-in CSS choices where the preview text or body text would overflow in some cases.

I ended up doing this for previews:

DIV.first_message {
font-size: 75%;
width: 80%;
text-align: left;
margin-left: 1em;
margin-bottom: 1em;
word-break: normal;
overflow-wrap: anywhere;
}


And this for messages like the 'g' one:

DIV.message_text {
margin: 1em;
word-break: normal;
overflow-wrap: anywhere;
}


I guess I'll add that to the NEMB custom CSS and see if it fixes it.