aside{min-width: 280px;max-width: 600px;width: 90%;margin-left: auto;margin-right: auto;text-align: center;}

.ifrm-wrap{
  min-width: 280px;
  max-width: 650px;
  background-color: #6666ff;
  margin: 0 auto;
  position: relative;
  width: 100%;
  padding: calc(650/650*100%) 0 0;
}

.ifrm-wrap iframe{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

/*-- アドバイス用のcss --*/

#main {
  background-color: #fff;
  padding: 1em;
}

h2 {
  margin-top: 1em;
}

strong {
  color: red;
  font-weight: bold;
}


img {
    width: 100%;
    max-width: 680px;
}

li {
	margin-left: 2em;
}

p {
  text-indent: 0.5em;
}

@media screen and (max-width: 500px) {
  .ifrm-wrap iframe {
    width: 200%;
    height: 200%;
    -moz-transform: scale(0.5,0.5);
    -webkit-transform: scale(0.5,0.5);
    -o-transform: scale(0.5,0.5);
    -ms-transform: scale(0.5,0.5);
    transform-origin:0 0;
    -o-transform-origin:0 0;
    -webkit-transform-origin:0 0;
    -moz-transform-origin:0 0;
    -ms-transform-origin:0 0;
  }
  #main {
    padding: 5px;
  }
}

@media screen and (min-width: 501px) {
  
}