Using Operator Mono in Atom

styles.less

/**
 * Using Operator Mono in Atom
 * 
 * 1. Open up Atom Preferences.
 * 2. Click the “Open Config Folder” button.
 * 3. In the new window’s tree view on the left you should see a file called “styles.less”. Open that up.
 * 4. Copy and paste the CSS below into that file. As long as you have Operator Mono SSm installed you should be golden!
 * 5. Tweak away.
 *
 * Theme from the screenshot (http://cdn.typography.com/assets/images/blog/operator_ide2.png):
 * 1. UI Theme: One Dark (comes with Atom, I believe) — https://github.com/atom/one-dark-syntax
 * 2. Syntax Theme: Oceanic Next — https://github.com/voronianski/oceanic-next-theme
 */

 atom-workspace,
 atom-text-editor {
    font-family: "Operator Mono SSm";
    font-size: 14px;
    font-weight: 400;
    line-height: 1.7;
 }
 atom-panel.tool-panel {
    font-size: 0.88em;
 }

For anyone else looking, the original has comments with more info on setting it up:

https://gist.github.com/brandondurham/3828ac42766f9f187c8e