#analyser {
    display: flex;
    align-items: flex-end;
    margin: 1em 0;
    height: 100px;
    border: 1px solid #ccc;
}

    #analyser > div {
        flex: 1;
        border-top: 2px solid green;
        transition: .1s;
    }

#piano {
    display: flex;
    margin: 0 auto;
    max-width: 80%;
}

    #piano > div {
        flex: 1;
        position: relative;
        height: 240px;
        margin: 0 1px;
        border: 1px solid #999;
        border-radius: 1px 1px 5px 5px;
        box-shadow: 2px 2px 5px rgba(0,0,0,.4);
        cursor: pointer;
    }

        #piano > div::after {
            position: absolute;
            bottom: 1em;
            width: 100%;
            text-align: center;
            content: attr(data-note);
            font-size: 1.5em;
        }

        #piano > div > div {
            position: absolute;
            top: -1px;
            left: 70%;
            height: 160px;
            width: calc(60% + 2px);
            background: #000;
            border-radius: 1px 1px 5px 5px;
            box-shadow: 2px 2px 5px rgba(0,0,0,.4);
            cursor: pointer;
            z-index: 10;
        }