gtk2/testsuite/css/parser/letter-spacing.ref.css

a {
  letter-spacing: initial;
}

b {
  letter-spacing: inherit;
}

c {
  letter-spacing: unset;
}

d {
  letter-spacing: 5px;
}

e {
  letter-spacing: 5em;
}

f {
  letter-spacing: 1in;
}