Menu colour does not change on hover

Here is the CSS I am using, change menu colour to black and background colour to white works fine, however colour is not changing to black on hover and stays white, I am using the following CSS

/* Change colour of background of top header menu */
.page nav.navbar.navbar-custom{
background: #ffffff !important;
}
/* Change colour of menu text on top header menu */
.navbar-custom .nav li > a{
color: #000000;
}
/*Change menu colour on hover – does not seem to work */
.navbar-custom .nav li > a:hover {
transition: 0.3s ease;
background: #fff;
color: #000;
font-size: 15px;
text-decoration: none;
border-top: 2px solid #000;
border-bottom: 2px solid #000;
padding: 10px 0;
margin: 0 20px;
}

any help appreciated
Thanks

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