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It's a bummer I need the wrapping spans. 
I can't see a way to achieve this (nicely positioning the <del>s) without them... can you?
My only idea is making the <del> be 'fixed' e.g. to the top or bottom, rather than a tooltip.
  brown fox 
  over the 


                html { box-sizing: border-box; } *, *::before, *::after { box-sizing: inherit; }
html {
  height: 100vh;
  font-size: 10px;
body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(to bottom, #7474bf, #348ac7);
  color: #fff;
  font-family: system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Oxygen-Sans,Ubuntu,Cantarell,"Helvetica Neue",sans-serif;
  font-size: 3rem;
  font-weight: 200;
span {
  position: relative;
del {
  text-decoration: none;
  background: #f44336;
  position: absolute;
  font-size: 1.4rem;
  bottom: -3.7rem;
  padding: .5rem;
  left: 50%;
  filter: drop-shadow(0 0 .2rem rgba(0,0,0,0.3));
  opacity: 0;
  transform: translate(-50%, -1rem);
  transition: all .15s ease-in;
  &::after {
    position: absolute;
    content: '';
    border: .5rem solid #f44336;
    border-color: transparent transparent #f44336;
    top: -1rem;
    left: 50%;
    transform: translateX(-50%);
  &::before {
    content: 'Was: ';
    white-space: nowrap;
ins {
  cursor: help;
  text-decoration: none;
  padding: 2px 5px;
  animation: fadeInIns .25s 1s ease-in forwards;
  &:hover {
    &+del {
      opacity: 1;
      transform: translate(-50%, 0);

//not really required, just for fading the green in first time
@keyframes fadeInIns {
  from { background: transparent }
  to { background: #6db723 }