Find where the comment_form() function is called. Usually it will be in the comments.php file of your WordPress theme.
It might be displayed like:
<?php comment_form(); ?>
Pass an argument to the function as below:
<?php comment_form(array('comment_notes_after' => '')); ?>
The array can have other arguments as well to mod the comment form to your liking. Refer to WordPress comment form codex for all possibilities.
There is some problem with Gmail display in Opera since past few months and no one from Opera or Google seems to be bothered about Opera users. A quick (but temporary) solution is to switch Gmail to basic HTML view. Open a new window or tab and access basic HTML Gmail by using the following URL:
https://mail.google.com/mail/?ui=html
Please remember, this is a temporary solution and many Gmail features will not be available.