etherpad-lite/src/static/css/pad/layout.css

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  margin: 0;
  padding: 0;
}
body {
  display: flex;
  flex-direction: column;
}
#editbar {
  height: auto;
}
#editorcontainerbox {
  flex: 1 auto;
  position: relative; /* for nested popup to use absolute positionning */
  background-color: #eee;

  /* For sticky chat */
  display: flex;
  flex-direction: row;
  height: 0; /* strange bug some browser need this to be working ok */
}
#editorcontainerbox #editorcontainer {
  display: flex; /* transfer flex properties to nested elements, here the iframe */
  height: auto;
  flex: 1 auto;
}
#editorcontainerbox #editorcontainer iframe {
  width: 100%;
  height: auto;
}
#editorcontainerbox .sticky-container { /* container for #users, #chat, #toc (table of content) and so on... */
  display: flex;
  flex-direction: column;
  width: 200px;
  max-width: 40%;
  flex-shrink: 0;
}
#editorcontainerbox .sticky-container:not(.stikyUsers):not(.stickyChat) {
  width: 0; /* hide when the container is empty */
}

@media only screen and (max-width: 720px) {
  #editorcontainerbox {
    margin-bottom: 39px; /* Leave space for the bottom toolbar on mobile */
  }
}