bbPress.org

hmm, not suer why your bbpress.css file is in wp-content/plugins/templates rather than wp-content/plugins/bbpress/templates – have you altered this?

In essence you want to set

.bbp-reply-author width :100% ;
.bbp-reply-content margin : 0px;

This will force the content to the next line, and move it to the start of that line.

I’d also add

#bbpress-forums div.bbp-reply-author img.avatar {
position: relative;
}

so you’d end up with (untested)

@media only screen and (max-width: 480px) {

.bbp-reply-author  {
width :100% ;
}
.bbp-reply-content {
margin : 0px;
}

#bbpress-forums div.bbp-reply-author img.avatar {
	position: relative;
	}

}