If you’re using WordPress visual editor, you may want to change the default font to a new one of your choice. Simply follow this simple recipe to get the job done. Nothing complicated. Simply open your functions.php file and paste the following code:

add_action( 'admin_head-post.php', 'devpress_fix_html_editor_font' );
add_action( 'admin_head-post-new.php', 'devpress_fix_html_editor_font' );

function devpress_fix_html_editor_font() { ?>
<style type="text/css">#editorcontainer #content, #wp_mce_fullscreen { font-family: Georgia, "Times New Roman", "Bitstream Charter", Times, serif; }</style>
<?php }

Once you saved the file, the editor font is changed to Georgia. Of course, feel free to modify the code to display your favorite font.