@media(max-width:700px){
  html,body{margin:0!important;padding:0!important}
  #chapter2Pane .chapter03-shell{
    width:min(100% - 12px,520px)!important;
    margin:0 auto!important;
    padding-top:4px!important;
  }
  .site-nav-v15{margin:5px auto 6px!important}
  .site-nav-v15 a{min-height:32px!important;padding:4px 9px!important;font-size:11px!important}

  /* compact section heading / challenge area */
  #chapter2Pane .net-divider{margin:4px 0 6px!important;padding-top:4px!important;padding-bottom:4px!important}
  #chapter2Pane .quiz-card,
  #chapter2Pane [class*="quiz-card"]{margin-top:5px!important;margin-bottom:6px!important;padding-top:10px!important;padding-bottom:10px!important}

  /* keep 3D large enough to operate, but avoid excessive vertical height */
  #chapter2Pane iframe{
    width:100%!important;
    max-width:100%!important;
    height:min(52vh,430px)!important;
    min-height:330px!important;
    display:block!important;
  }

  .separate-page-nav{
    margin:7px 2px 5px!important;
    padding:5px!important;
  }
  .separate-page-nav a{
    min-height:32px!important;
    padding:5px 4px!important;
    font-size:11px!important;
  }
}
@media(max-width:390px){
  #chapter2Pane iframe{height:46vh!important;min-height:300px!important}
}