metamask-extension/ui/app/css/debug.scss

/*
debug / dev
*/

#app-content {
  border: 2px solid green;
}

#design-container {
  position: absolute;
  left: 360px;
  top: -42px;
  width: calc(100vw - 360px);
  height: 100vh;
  overflow: scroll;
}

#design-container img {
  width: 2000px;
  margin-right: 600px;
}