:octocat: add default value for QRMarkup::getCssClass()

src/Output/QRMarkup.php

@@ -82,7 +82,7 @@ abstract class QRMarkup extends QROutputAbstract{
 	/**
 	 * returns a string with all css classes for the current element
 	 */
-	protected function getCssClass(int $M_TYPE):string{
+	protected function getCssClass(int $M_TYPE = 0):string{
 		return $this->options->cssClass;
 	}
 

src/Output/QRMarkupHTML.php

@@ -23,7 +23,7 @@ class QRMarkupHTML extends QRMarkup{
 	protected function createMarkup(bool $saveToFile):string{
 		$html = empty($this->options->cssClass)
 			? '<div>'
-			: sprintf('<div class="%s">', $this->getCssClass(0)); // @todo $M_TYPE
+			: sprintf('<div class="%s">', $this->getCssClass());
 
 		$html .= $this->options->eol;
 

src/Output/QRMarkupSVG.php

@@ -142,7 +142,7 @@ class QRMarkupSVG extends QRMarkup{
 	/**
 	 * @inheritDoc
 	 */
-	protected function getCssClass(int $M_TYPE):string{
+	protected function getCssClass(int $M_TYPE = 0):string{
 		return implode(' ', [
 			'qr-'.($this::LAYERNAMES[$M_TYPE] ?? $M_TYPE),
 			(($M_TYPE & QRMatrix::IS_DARK) === QRMatrix::IS_DARK) ? 'dark' : 'light',