Submenu not doing dropdown

Can someone tell me why my submenu is always being displayed? I want it to appear when hovering, but it is always visible ...

CSS:

/* submenu */
.sub-menu {
    width: 100%;
    padding: 5px 0px;
    position: absolute;
    top: 100%;
    left: 0px;
    background: #fff;
    box-shadow: 0px 6px 9px rgba(0, 0, 0, 0.25);
    border-bottom-left-radius: 5px;
    border-bottom-right-radius: 5px;
    transition: all .5s ease-in-out;*/
}


 .menu li:hover .sub-menu {
    z-index: 1;
    opacity: 1;
} 


.sub-menu li {
    display: block;
    font-size: 75%;
    text-align: center;
}

.sub-menu li a {
    position: relative;
    padding: 15px 30px;
    display: block;
    text-decoration: none;
    color: #74C8D2;
}



.sub-menu li a:hover,
.sub-menu .current-item a {
    display: block;
    background: #74C8D2;
    color: #fff;
    transition: .5s ease-in-out;
}

Thank you!