@logo: url(ebay-logo.png);

.foo {
    background-image: @logo;
}

.bar {
    background-image: url(ebay-logo.png);
}

.baz {
    background-image: url(http://baz.com/baz.png);
}

.data-image {
    background-image: url(data:image/svg+xml;base64,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);
}

.data-image-utf8 {
    width: 10px;
    height: 10px;
    background-image: url("data:image/svg+xml;utf8,foo()bar()");
}