base-grid.css in Panels Extra Layouts 7.2

/* base-grid.css --- 
   Copyright (C) 2010 António P. P. Almeida <appa@perusio.net>

   Author: António P. P. Almeida <appa@perusio.net>

   This program is free software, you can redistribute it and/or
   modify it under the terms of the new-style BSD license.
   You should have received a copy of the BSD license along with this
   program. If not, see <http://www.debian.org/misc/bsd.license>.

   Inspired & stolen from Nicole Sullivan's OOCSS http://oocss.org
   This file is the base grid for the tinycss framework. */

@media screen and (max-width: 319px) {
.unit {
    float: none !important; 
    width: auto !important;
  }
}

.line:after, .lastUnit:after {
  clear: both;
  display: block;
  visibility: hidden; 
  overflow:hidden;
  height:0 !important;
  line-height: 0;
  font-size: xx-large;
  content: " x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x ";
}

.unit {
  float: left;
}

.lastUnit {
  display: table-cell;
  float: none;
  width: auto;
}