How to display “Classic” built-up fractions with an horizontal line in CSS / JavaScript?

Question

I have a fraction and I want to display it neatly and nicely.

For example

4/5

would be

4
-
5

I have looked at this and

Answer 1

Flexbox now allows some additional options

.fraction {
  display: inline-flex;
  flex-direction: column;
  padding: 1em;
  align-items: center;
}
.numerator {
  border-bottom: 2px solid grey;
}

  3
  4



  12
  7