.contenedor {
    float: right;
     width:100%;
  border: 2px solid #ccc;
  background-color: #eee;
  border-radius: 5px;
  padding: 16px;
  margin: 16px 0
}

.caja{
     width:100%;
  border: 2px solid #ccc;
  background-color: #eee;
  border-radius: 5px;
  padding: 16px;
  margin: 16px 0
}

.contenedor::after {
  content: "";
  clear: both;
  display: table;
}

.contenedor img {
  float: left;
  margin-right: 20px;
  border-radius: 50%;
}

.contenedorspan {
  font-size: 20px;
  margin-right: 15px;
}

@media (max-width: 500px) {
  .contenedor {
      text-align:justify-all;
  }
  .contenedor img {
      margin: auto;
      float: none;
      display: block;
  }
}