Edit line thickness of CSS 'underline' attribute

Question

Since you can underline any text in CSS like so:

h4 {
    text-decoration: underline;
}

How can you also then edit the \'line\' that is drawn

Answer 1

a {
  text-decoration: none;
  position: relative;
}

a.underline {
  text-decoration: underline;
}

a.shadow {
   box-shadow: inset 0 -4px 0 white, inset 0 -4.5px 0 blue;
}

Default: some text alpha gamma
the quick brown fox
Working:
Using Shadow: some text alpha gamma
the quick brown fox
even works with
multiple lines

Final Solution: http://codepen.io/vikrant-icd/pen/gwNqoM

a.shadow {
   box-shadow: inset 0 -4px 0 white, inset 0 -4.5px 0 blue;
}