User CSS to display element IDs where applicable. (Running this in your regular browsing will _break everything_, so don't!)

show-ids.css

*[id]:before {
  box-sizing: border-box;
  content: "#"attr(id);
  display: inline-block;
  background-image: -webkit-gradient( radial, 50% 100%, 0, 50% 100%, 100, from(rgba(89, 208, 244, 1)), to(rgba(89, 208, 244, 0))), -webkit-gradient(linear, 0% 0%, 0% 100%, from(#4FBBF7), to(#3FAEEB));
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 9px;
  font-weight:lighter;
  text-align:center;
  line-height: 12px;
  width: 100%;
  color: rgb(15,75,109);
  border: 1px solid #84ACC3;
  z-index: 9999;
  border-radius: 0.4em;
  padding-left: 0.4em;
  padding-right: 0.4em;
  box-shadow: 0em 0.2em 0.5em black;
  overflow: hidden;
}