/*
iframe {
  resize: both;
  overflow: hidden;
}

h1 {
  color: red;
}

iframe {
  resize: both;
  overflow: hidden;
}

iframe {
  width: 400px;
  resize: both;
  overflow: auto;
}

.resizer { display:flex; margin:0; padding:0; resize:both; overflow:hidden }
.resizer > .resized { flex-grow:1; margin:0; padding:0; border:0 }

.ugly { background:red; border:4px dashed black; }
*/