#game_div {
    margin: 0;
    padding: 0;
    font-family: sans-serif;
    background-color: #f7f7f7;
}

span {
    color: #31383a;
}

#game_end {
    height: 100%;
    width: 100%;
    position: absolute;
    z-index: 1;
    background-color: rgba(255, 255, 255, 0.9);
    text-align: center;
    display: none;
}

/* https://getbootstrap.com/docs/4.0/components/buttons/ */
#game_end button {
    color: #fff;
    background-color: #28a745;
    border-color: #28a745;
    font-weight: 400;
    text-align: center;
    white-space: nowrap;
    vertical-align: middle;
    border: 1px solid transparent;
    user-select: none;
    cursor: pointer;
    padding: .375rem .75rem;
    font-size: 1rem;
    line-height: 1.5;
    border-radius: .25rem;
}

#game_end a {
    color: #fff;
    background-color: #007bff;
    border-color: #007bff;
    text-decoration: none;
    font-weight: 400;
    text-align: center;
    white-space: nowrap;
    vertical-align: middle;
    border: 1px solid transparent;
    user-select: none;
    cursor: pointer;
    padding: .375rem .75rem;
    font-size: 1rem;
    line-height: 1.5;
    border-radius: .25rem;
}

#scoreboard {
    margin: 0px 30px 0px 30px;
    height: 6%;
    line-height: 250%;
    vertical-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 100px;
}

#score {
    float: right;
}

#notification {
    position: absolute;
    top: 0px;
    width: 100%;
    background-color: #f7f7f7;
    padding: 20px;
    text-align: center;
    display: none;
    border: 1px solid black;
    border-radius: 5px;
}

#top_shelf,
#bottom_shelf {
    height: 47%;
    width: 100%;
}

#bottom_shelf {
    background-color: #f7f7f7;
}

/* https://stackoverflow.com/questions/18781713/css-divide-width-100-to-3-column */
#top_shelf {
    display: flex;
    height: 47%;
}

#top_shelf>div {
    flex-grow: 1;
    color: white;
    text-align: center;
    font-weight: lighter;
    height: 300px;
}

#top_shelf>div h2 {
    font-weight: lighter;
    margin-top: 15px;
    font-size: 25px;
    font-weight: 400;
}

#top_shelf>div:first-of-type {
    background-color: #E66A26;
}

#top_shelf>div:nth-of-type(2) {
    background-color: #31383a;
}

#top_shelf>div:nth-of-type(3) {
    background-color: #DE2620;
}

#top_shelf>div:nth-of-type(4) {
    background-color: #448BE3;
}

#top_shelf>div:nth-of-type(5) {
    background-color: #71C038;
}

#bottom_shelf img {
    position: absolute;
    cursor: move;
}

@media only screen and (max-width: 500px) {
    #bottom_shelf img {
        width: 50px;
        height: 50px;
    }
}