Customising Font Spacing

Hi team, in the ‘Use any font’ uploader there is a section for custom CSS. Can I use a standard:

h1 {
  letter-spacing: 5px;
}

For each area I want it activated? I tried the above and it didn’t work. Let me know how I can perhaps adjust the font spacing that is being activated.

Thank you!

The page I need help with: [log in to see the link]