html, body {
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
}

.elements {
    position: fixed;
    left: 0;
    right: 0;
    width: 300px;
    bottom: 0;
    top: 0;
    background-color: #58c26f;
}

.play-area {
    position: fixed;
    left: 300px;
    right: 0;
    bottom: 0;
    top: 0;
}

.play-area .item {
    width: 100px;
    height: 50px;
    background-color: red;
    position: absolute;
    border: 1px solid #000;
    text-align: center;
    user-select: none;
}

.play-area .item.no-select {
    user-select: none;
}

.play-area .overlay-mask {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 999;
}