php - whitespace removed in html tag -

my current problem jbbcode library. when use tag ( know depreceated ), tag parameter become x size.

my code :

 $font_size = '<font size="{option}">{param}</font>';         $builder = new codedefinitionbuilder('size', $font_size);         $builder->setuseoption(true)->setoptionvalidator(new \jbbcode\validators\csscolorvalidator());         $this->definitions[] = $builder->build(); 

the result :

so how can force whitespace in tag ?