/**
 * Initialiazing a `footnotes` counter on the wrapper
 */
article {
  counter-reset: footnotes;
}

/**
 * Inline footnotes references
 * 1. Increment the counter at each new reference
 * 2. Reset link styles to make it appear like regular text
 */
a[aria-describedby="footnote-label"] {
  counter-increment: footnotes; /* 1 */
  text-decoration: none; /* 2 */
  color: inherit; /* 2 */
  cursor: default; /* 2 */
  outline: none; /* 2 */
}

/**
 * Actual numbered references
 * 1. Display the current state of the counter (e.g. `[1]`)
 * 2. Align text as superscript
 * 3. Make the number smaller (since it's superscript)
 * 4. Slightly offset the number from the text
 * 5. Reset link styles on the number to show it's usable
 */
a[aria-describedby="footnote-label"]::after {
  content: '[' counter(footnotes) ']'; /* 1 */
  vertical-align: super; /* 2 */
  font-size: 0.5em; /* 3 */
  margin-left: 2px; /* 4 */
  color: blue; /* 5 */
  text-decoration: underline; /* 5 */
  cursor: pointer; /* 5 */
}

/**
 * Resetting the default focused styles on the number
 */
a[aria-describedby="footnote-label"]:focus::after {
  outline: thin dotted;
  outline-offset: 2px;
}

footer :target {
  background: yellow;
}