If you recently upgraded wordpress to the latest 3.2.x version, you will notice that the fonts for the HTML editor has changed. If you do not like the font that is used you can change font by adding a filter in theme function.php file to what ever font you fill comfortable with.
You can change font directly by editing the wp-admin.css file under the “wp-admin -> css” folder. This is not adviced because the next time you upgrade your WordPress, your files will be overwritten.
You need make a back up of functions.php file before you add the code just in case you make a mistake and you need to go back to the way your wordpress was before you added the code. To go back before the change you need to delete the functions.php file and re upload the backup.
The best way is to insert a small function to your functions.php.
Click on Appearance >>>Themes>>>Editor and open functions.php file from right.
Add the following code after
<?php
add_action( 'admin_head-post.php', 'fix_html_editor_font' );
add_action( 'admin_head-post-new.php', 'fix_html_editor_font' );
function fix_html_editor_font() { ?>
<style type="text/css">#editorcontainer #content, #wp_mce_fullscreen
{ font-family: Verdana,Tahoma,Arial,Helvetica; }</style>
<?php }
and save the file
You can change the font-family to the one you like by changing the last line I personally prefer the Verdana .
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