.lazyload,
.lazyloading {
    opacity: 0
}

.lazyloaded {
    opacity: 1;
    transition: opacity 300ms
}

.lazyload {
    opacity: 0
}

.lazyloading {
    opacity: 1;
    transition: opacity 300ms;
    background: #f7f7f7 url(./loading.gif) no-repeat center
}