fix_aa_font.user.js

// ==UserScript==
// @name           FixAAFont
// @namespace      http://d.hatena.ne.jp/javascripter/
// @include        http*
// ==/UserScript==

var xpr = document.evaluate('descendant-or-self::*[contains(text(), "／")]/ancestor-or-self::div', document.body, null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
for (var i = 0; i < xpr.snapshotLength; ++i) {
  var elem = xpr.snapshotItem(i);
  var prefix = elem.className ? ' ' : '';
  elem.className += prefix + 'ascii-art';
}