Customisation for @atomeditor with smaller font/icons on the sidebar (tree)

styles.less

/* 
 * Smaller icons and fonts for the sidebar (tree view). 
 * Based on SD's tweaks: https://gist.github.com/sd
 */

.tree-view {
  font-size: 12px;
  .list-item {
    line-height: 20px !important;
  }
  .selected:before, .selected:before {
    height: 20px !important;
  }
  .icon:before {
    font-size: 11px;
    width: 10px;
    height: 10px;
    opacity: .6;
    position: relative;
    top: 0px;
  }
  .header:before {
    font-size: 10px !important;
    opacity: .6;
    margin-right: 0px !important;
  }
}

/* more subtle invisibles */
.editor {
  .invisible-character {
    opacity: .2;
  }
  .indent-guide {
    opacity: .4;
  }
}

/* thicker cursor */
.editor .cursor {
  border-left-width: 2px;
}