RewriteEngine On 

 RewriteRule ^category/([a-zA-Z0-9-/]+)$ category.php?curl=$1  
 RewriteRule ^category/([a-zA-Z-0-9-]+)/ category.php?curl=$1

 RewriteRule ^product/([a-zA-Z0-9-/]+)$ product.php?url=$1  
 RewriteRule ^product/([a-zA-Z-0-9-]+)/ product.php?url=$1  