html,
body,
#root {
    height: 100%;
}

.box-container {
    position: relative;

    .box {
        display: block;
        position: absolute;
        width: 50px;
        height: 50px;
        top: 100px;
        left: 0px;
        background-color: #ee8;
        border: 1px solid #420;
    }
}