How to add H4 and H5 on Brine Template using Index Pages

Site URL: https://flatworm-oleander-welg.squarespace.com

I am trying to add an H4 and H5 font to the Brine template. Using CSS, I've succeeded at changing the font size and color but no change to the font-family, Omnes Pro.

Omnes Pro is the font family I selected from the Brine template for H1-H3. 

I want to use the H4 and H5 font on the secondary pages in the banners. These secondary pages are index pages. 

I'm new to CSS. Below is the code I used. Any help would be greatly appreciated!!

/*ADDITIONAL FONTS IN BRINE*/
h4 {
  color: white;
  font-family: "Omnes Pro" !important;
  font-weight: 500;
  font-style: normal;
  font-size: 17px;
  letter-spacing: .05em;
  text-transform: none;
  line-height: 1.4em;
}

h5 {
  color: white;
  font-family: "Omnes Pro"!important;
  font-weight: 500;
  font-style: normal;
  font-size: 60px;
  letter-spacing: .05em;
  text-transform: none;
  line-height: 1.2em;
}

your font name is incorrect. It should be

font-family: omnes-pro !important;