Operator Moni + Fire for Atom

style.less

atom-text-editor {
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  font-family: "Operator Mono";
  font-weight: 500;
}

atom-text-editor.editor {
  .syntax--storage.syntax--type.syntax--function.syntax--arrow,
  .syntax--keyword.syntax--operator:not(.accessor),
  .syntax--punctuation.syntax--definition {
    font-family: "Fira Code";
  }

  .syntax--string.syntax--quoted,
  .syntax--string.syntax--regexp {
    -webkit-font-feature-settings: "liga" off, "calt" off;
  }
}