Customize the font size of Atom's file tree and tab bar

styles.less

/*
 * Your Stylesheet
 *
 * This stylesheet is loaded when Atom starts up and is reloaded automatically
 * when it is changed.
 *
 * If you are unfamiliar with LESS, you can read more about it here:
 * http://www.lesscss.org
 */

atom-text-editor::shadow .comment {
  font-style: normal;
}

@font-size: 13px;
html, body, .tree-view, .tab-bar .tab {
  font-size: @font-size;
}

.settings-view {
  .settings-panel label,
  .breadcrumb,
  .setting-title,
  .package-card
  .package-readme {
    font-size: 1rem;
  }
}