CSS to add a white or black alpha hover state on any colour button. This allows a single hover state to be applied to buttons of multiple colours without having to manually set colours.

button.css

.orange{ background: #ff7a4d; }
.blue{ background: #7396ff; }

.button {
    display: inline-block;
    *display: inline;
    color: #ffffff;
    text-decoration: none;
    padding: 6px 10px;
    position: relative;
}
.button:hover {
    color: #ffffff;
}
.button:hover:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.3);
}
.button.dark:hover:before {
    background: rgba(0, 0, 0, 0.2);
}

sample.html

<!-- Light hover -->
<a href="#" class="button orange">What, How, Why? Find Out &raquo;</a>

<!-- Dark hover -->
<a href="#" class="button dark blue">What, How, Why? Find Out &raquo;</a>