<!DOCTYPE html>
<style>
.box {
    display: inline-block;
    height: 100px;
    width: 300px;
    margin: 10px;
    border: 1px solid black;
    background-repeat: no-repeat;
}

.linear {
    background-image: -webkit-linear-gradient(left, white 310px, green 300px);
    background-image: -moz-linear-gradient(left, white 310px, green 300px);
}
</style>
<h2>This should be an empty box</h2>
<div class="linear box"></div>