protected function injectCSS() {
            if (!$this->isCLI && !self::$cssInjected) {
                self::$cssInjected = true;
                if (file_exists($this->config->cssPath)) {
                    echo '<style type="text/css">';
                    /** @noinspection PhpIncludeInspection */
                    include $this->config->cssPath;
                    echo '</style>';
                } else {
                    echo 'The AloFramework handlers\' CSS file could not be found: ' . $this->config->cssPath . PHP_EOL;
                }
            }
        }