public function set_inline_css($attribute, $value, $group_name = false)
{
if ($group_name !== false) {
if (!isset($this->inline_css_groups[$group_name])) {
$this->inline_css_groups[$group_name] = '';
}
$this->inline_css_groups[$group_name] .= $attribute . ': ' . $value . ';';
} else {
$this->inline_css .= $attribute . ':' . $value . ';';
}
}