Transparency Mixin
</> = opacity (! Opacity)
</> opacity:! Opacity
/ * para todos os bons navegadores * /
</> – moz-opacity:! opacity
/ * para Mozilla e Netscape * /
</> – khtml-opacity:! opacity
/ * para Safari e Webkit * /
</> – ms-filter: “progid: DXImageTransform.Microsoft.Alpha (Opacity =” + round (! opacity 100) + “)”
/ para IE 8 * /
</> filtro: “alpha (opacity =” + round (! opacity 100) + “)”
/ para IE 5-7 * /