responsive.css

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial;
}

.header {
  text-align: center;
  padding: 32px;
}

.row {
  display: -ms-flexbox; /* IE10 */
  display: flex;
  -ms-flex-wrap: wrap; /* IE10 */
  flex-wrap: wrap;
  padding: 0 2px;
}

/* Create two equal columns that sits next to each other */
.column_left, .column_right {
  -ms-flex: 50%; /* IE10 */
  flex: 50%; 
  max-width: 50%;
  padding: 4px 4px 0 4px;
}

.column_left img{
  vertical-align: middle;
  width: 100%;
}
.column_right img{
   vertical-align: middle;
  width: 100%; 
}

.end_image{
  max-width: 50%;
  padding: 0;
  display: block;
  margin-left: auto;
  margin-top: 0;
  margin-right: auto;

}

.end_image img{
  vertical-align: middle;
  width: 100%;

}

/* Responsive layout - makes a two column-layout instead of four columns 
@media screen and (max-width: 800px) {
  .column {
    -ms-flex: 50%;
    flex: 50%;
    max-width: 50%;
  }
}
*/

/* Responsive layout - makes the two columns stack on top of each other instead of next to each other */
@media screen and (max-width: 1000px) {
  .column_left{
    -ms-flex: 100%;
    flex: 100%;
    max-width: 100%;
    margin: 0 .8em 0 0;
  }
  .column_right{
    -ms-flex: 100%;
    flex: 100%;
    max-width: 100%;
    margin: 0 0 0 .8em;
  }
  .end_image{
    -ms-flex:100%;
    flex: 100%;
    max-width: 100%;
    margin: 0 1.2em 0 1em;
  }
}