AdminLTE/build/scss/pages/_iframe.scss

body.iframe-mode {
  .main-sidebar {
    display: none;
  }
  .content-wrapper {
    margin-left: 0 !important;
  }
  .main-header,
  .main-footer {
    display: none;
  }
}

.content-wrapper {
  height: 100%;

  &.iframe-mode {
    iframe {
      border: 0;
      width: 100%;
      height: 100%;
    }
  }
}