Normal text:

iiiii Some {{template}} <tag>
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

TT tags:

iiiii Some {{template}} <tag> (Some normal text for height comparison)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

CODE tags:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

PRE tags:

iiiii Some {{template}} <tag>
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

SOURCE tags:

iiiii Some {{template}} <tag>
mmmmm 0123456789 abcdefghij ABCDEFGHIJ


<span style="font-family: monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<tt style="font-family: monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<code style="font-family: monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<pre style="font-family: monospace;">:

iiiii Some {{template}} <tag>
mmmmm 0123456789 abcdefghij ABCDEFGHIJ


<span style="font-family: monospace, sans-serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<tt style="font-family: monospace, sans-serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<code style="font-family: monospace, sans-serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<pre style="font-family: monospace, sans-serif;">:

iiiii Some {{template}} <tag>
mmmmm 0123456789 abcdefghij ABCDEFGHIJ


<span style="font-family: monospace, serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<tt style="font-family: monospace, serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<code style="font-family: monospace, serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ


<span style="font-family: monospace, monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<tt style="font-family: monospace, monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<code style="font-family: monospace, monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ


<span style="font-family: sans-serif, monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<tt style="font-family: sans-serif, monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<code style="font-family: sans-serif, monospace;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ


<span style="font-family: monospace, courier, serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<tt style="font-family: monospace, courier, serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ

<code style="font-family: monospace, courier, serif;">:

iiiii Some {{template}} <tag> (normal text)
mmmmm 0123456789 abcdefghij ABCDEFGHIJ


Explanation: Some browsers on some operating systems show <tt>, <code>, <pre> and <source> tagged text in a too small font. At the time I write this (21 December 2009) we have applied the code below to MediaWiki:Common.css and MediaWiki:Geshi.css, which seems to fix it for those browsers, and cause no problems in the rest of the browsers. If it works well for the English Wikipedia, then we might deploy the fix for all Wikimedia projects. See discussion at Teletype style fix for Chrome.

/* Fix so <tt>, <code> and <pre> tags get normal text size also in 
   some versions of Firefox, Safari, Konqueror, Chrome etc. */
tt, code, pre {
    font-family: monospace, sans-serif;
}

/* Fix so <syntaxhighlight lang=""> tags, and .css and .js pages, get normal text size 
   also in some versions of Firefox, Safari, Konqueror, Chrome etc. */
div.mw-geshi div,
pre {
  font-family: monospace, sans-serif !important;
}