Active links on main menu

Hi, could you help me?
I have a problem to set opacity:1; on the active link (the link of the current page), i’ll explain better :

1) this is my url site : http://www.hattusas.it
2) I set “css classes (optional)” for every item of the menu (ex: “item_home” for the home link)
3) I uploaded an icon in the media library for every item of the menu
3) I changed “custom.css” adding : this code for every link of the menu

.item_home {
background: url(https://www.hattusas.it/wp-content/uploads/2014/02/home_icon.png) no-repeat center; 
text-align: center;
width: 60px;
opacity: 0.4;
}

.item_home:hover {
opacity:1;
}

that work very well but i’m not able to set the opacity:1 for the active page.
I tried using this code and similar in the custom css :

.current-menu-item > a {
opacity:1 !important;
}

but doesn’t work, could you help me?
thank you! :)