Q&A - Core / wp-header inline css problem

In Q&A plugin in core.php there is function

function wp_head() {
		$width = $this->_get_content_width();
?>
<style type="text/css">
<?php
if (get_template() == 'bp-default') {
	$bp_max_width = 1200;
	$bp_min_width = 920;
?>
div#sidebar { margin-left: 0; }
div#content .padder { margin-right: 0; }
#qa-page-wrapper, #content { width: 80%; max-width: <?php echo $bp_max_width - 212; ?>px; min-width: <?php echo $bp_min_width - 210; ?>px }
#question-form table { max-width: <?php echo $bp_max_width - 210 - 6; ?>px; min-width: <?php echo $bp_min_width - 210 - 6; ?>px }
.question-summary { max-width: <?php echo $bp_max_width - 210 - 116; ?>px; min-width: <?php echo $bp_min_width - 210 - 116; ?>px }
<?php
} else {
?>
#qa-page-wrapper { width: <?php echo $width; ?>px; }
#question-form table { width: <?php echo $width - 6; ?>px; }
.question-summary { width: <?php echo $width - 156; ?>px; }
<?php } ?>
</style>
<?php
	}

	function _get_content_width() {
		return isset( $GLOBALS['content_width'] ) ? $GLOBALS['content_width'] : 620;
	}

The problem is, that after changing the width of #qa-page-wrapper in css, it doesn't take any effect cuz its in core and is printed in header.

1) why the css styles are printed as hardcoded in to the header.
2) how the hell i can change the width of 620 wihtout touching the core.php file?

Throw generat.css file it doesn't take any effect. In plugin no setting is included that give an option to override this function. So why this code even exist to define width to 620px?

Will appreciate any help with this