* {
      box-sizing: border-box;
    }
    
    html, body {
      height:100%;margin:0px;padding:0px;
    }
    
    .frame-container {
      display:flex;flex-direction:column;
      height:4000px;overflow:hidden;
      margin:0px;padding:0px;border:0px solid green;
    }

    .frame {
      width:100%;height:100%;/* use overflow:hidden in page-container to avoid scrollbar */  
      margin:0px;padding:0px;border:0px solid blue;
    }