How to put php code in the style attribute of a div element?
You don't have to rewrite <?php ?>, just like this:
echo "<div style='width:". $sirina." px;height:'". $visina." px;border:1px solid black;'";
you can use this syntax:
<?= ?>
you can put any variable between this tags and it will echo that variable automatically.
so your code will refactor to this:
echo "<div style='width:<?= $sirina ?>;height: <?= $visina ?>;border:1px solid black;'";