Template:Ambox/styles.css

@media (max-width:640px) {  /* Responsive web design */
/* Making message boxes (e.g. [[Template:Nutshell]]) useable on narrow screens */
    .mbox, .ambox, .ombox 
     { margin: 0;
       width: 100%;
     }
    .mbox-image { vertical-align: top; }
    /*.mbox-image div { width: 30px!important; }*/ 
      /* Currently unneeded due to float */

    /* Floating icon saves even more screen space */
    .mbox, .ambox, .ombox tbody { padding: 1em; }
    .mbox-image { float:left; }
    .mbox, .ambox, .ombox td,
    .mbox, .ambox, .ombox div { display:inline; }

    /* Padding patch */
    th.mbox-text, 
    td.mbox-text  { padding: 0; }
    td.mbox-image { padding: 0.1em 0.5em; }
    .mbox, .ambox, .ombox    { padding:0.2em; display:block; }
}


/* Implementing floatbox class */
table.ambox.floatbox,
 table.mbox.floatbox,
           .floatbox {
  float:  right;
  clear:  right;
  width:  309px;
  margin: 0 0 1em 1.4em;
}


@media (max-width:639px) {
    table.ambox.floatbox,
     table.mbox.floatbox,
               .floatbox {
    float:  none;
    clear:  both;
    width:  100%;
    margin: 0;
  }
}

This template "Ambox/styles.css" is from Wikipedia if otherwise notified