code: function alignHorizontally(cm) {
      var display = cm.display;
      if (!display.alignWidgets && (!display.gutters.firstChild || !cm.options.fixedGutter)) return;
      var comp = compensateForHScroll(display) - display.scroller.scrollLeft + cm.doc.scrollLeft;
      var gutterW = display.gutters.offsetWidth, l = comp + "px";
      for (var n = display.lineDiv.firstChild; n; n = n.nextSibling) if (n.alignable) {
        for (var i = 0, a = n.alignable; i < a.length; ++i) a[i].style.left = l;
      }
      if (cm.options.fixedGutter)
        display.gutters.style.left = (comp + gutterW) + "px";
    }
docs: LINE NUMBERS