Preview:
.iframe-container {
      // overflow: hidden;
      // /* 16:9 aspect ratio */
      // padding-top: 56.25%;
      // position: relative;
      width: 100%;
      padding-top: 100%;
      position: relative;
      iframe {
         // border: 0;
         // height: 100%;
         // left: 0;
         // position: absolute;
         // top: 0;
         // width: 100%;
         position: absolute;
         top: 0;
         left: 0;
         width: 100%;
         height: 100%;
      }
    }
downloadDownload PNG downloadDownload JPEG downloadDownload SVG

Tip: You can change the style, width & colours of the snippet with the inspect tool before clicking Download!

Click to optimize width for Twitter