<p>First of all, do not add any customization to the page header, because it is a violation to the
Help:Customization policy. Second of all, in terms of inline styling, you do the following:
</p>
<span style="border:1px solid red; padding: 4px">Loren ipsum</span>
<p>gives
</p><p><span style="border:1px solid red; padding: 4px">Loren ipsum</span>
</p><p>Also, let's say you have a class called "text-border", and you have the following code somewhere on a page:
</p>
<span class="text-border">Lorem ipsum</span>
<p>It is required to have the following code on
MediaWiki:Wikia.css in order to make it work:
</p>
<div dir="ltr" class="mw-geshi mw-content-ltr"><div class="css source-css">
<span class="re1">.text-border</span> <span class="br0">{</span> <span class="kw1">border</span><span class="sy0">:</span><span class="re3">1px</span> <span class="kw2">solid</span> <span class="kw2">red</span><span class="sy0">;</span> <span class="kw1">padding</span><span class="sy0">:</span> <span class="re3">4px</span> <span class="br0">}</span>
</div></div>
<p>The output would be identical, but the input would br different.
</p><p>Hope this helped!
</p>