I have developed a moodle form like this:
$mform =& $this->_form;
$mform->addElement('header', 'general', get_string('addnewidea', 'designproblem').designproblem_makelocalhelplinkmain ("addideas", "Help with Add a new idea", "designproblem"));
$mform->addElement('htmleditor', 'ideacontent', get_string('brainstormidea', 'designproblem'), array('rows'=>'15', 'cols'=>'50'));
$mform->setType('ideacontent', PARAM_RAW);
$mform->setHelpButton('ideacontent', array('writing', 'questions', 'richtext'), false, 'editorhelpbutton');
$mform->addRule('ideacontent', null, 'required', null, 'client');
$this->add_action_buttons($cancel = false, $submitlabel = get_string('addidea', 'designproblem'));
However, htmleditor is aligned right in Internet Explorer, and center in Firefox. Other elements looks fine.
How can I set it to be aligned center in all browsers?