instead of lightbox2. Because lightweight + responsive.

You have to download and upload lity and the newest version of Jquery.

lity.min.js **to** sites/default/assets/js/
new jquery.min.js **to** sites/default/assets/js/
lity.min.css **to** sites/default/assets/css/

Please don't forget to make backups of these files:

sys/Ext/Html.php
sites/default/assets/js/editor.js
sites/default/themes/default/templates/forum/topic.tpl
sites/default/themes/default/templates/user/profile/view.tpl
sites/default/themes/default/templates/layout.tpl

Open:

sys/Ext/Html.php

Change

68 'a' => array('href', 'target'),

To

68 'a' => array('href', 'target', 'data-lity'),

Save

Open:

sites/default/assets/js/editor.js

Change:

196 <img src="' + href + '" title="' + title + '" />
201 <img src="' + href + '" title="' + title + '" />
247 <a href="' + href + '"><img src="http://i.imgur.com/' + part[1] + '.jpg" title="' + title + '" /></a>
254 <img src="' + href + '" title="' + title + '" />

To:

196 <a href="' + href + '" data-lity="' + href + '" title="' + title + '"><img src="' + href + '" /></a>
201 <a href="' + href + '" data-lity="' + href + '" title="' + title + '"><img src="' + href + '" /></a>
247 <a href="' + href + '" data-lity="' + href + '" title="' + title + '"><img src="http://i.imgur.com/' + part[1] + '.jpg" /></a>
254 <a href="' + href + '" data-lity="' + href + '" title="' + title + '"><img src="' + href + '" /></a>

Save

Open:

sites/default/themes/default/templates/forum/topic.tpl

Find:

263 <link rel="stylesheet" type="text/css" href="{$smarty.const.DURI}assets/markitup/highlight/styles/github.css" />

Add before:

<script src="{$smarty.const.DURI}assets/js/lity.min.js"></script>
<link rel="stylesheet" type="text/css" href="{$smarty.const.DURI}assets/css/lity.min.css" />

Save

Open:

sites/default/themes/default/templates/user/profile/view.tpl

Find:

221 </script>

Add after:

<script src="{$smarty.const.DURI}assets/js/lity.min.js"></script>
<link rel="stylesheet" type="text/css" href="{$smarty.const.DURI}assets/css/lity.min.css" />

Save

Open

sites/default/themes/default/templates/layout.tpl

Find:

151  {$page.head.js}

Add after:

<script type="text/javascript" src="{$smarty.const.DURI}assets/js/jquery-1.11.3.min"></script>

Save