styles.css

#sim {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    margin: 0;
}


.panel {
    position: absolute;
    right: 0;
    top: 0;
    height: 100vh;
    border-left: 1px rgba(0, 0, 0, 0.3) solid;

    background: white;
}


.state-wrapper {
    width: 200px;
    overflow: hidden;
    list-style: none;

    padding: 0px;

    transition: width 1s;
}

.panel.closed .state-wrapper {
    width: 0px;
}

.state {
    border-top: 1px rgba(0, 0, 0, 0.3) solid;
    text-align: center;
    font-weight: bold;
    font-size: 25px;

    font-family: Arial, Helvetica, sans-serif;

    transition: background-color 600ms;

    -webkit-user-select: none; /* Safari */        
    -moz-user-select: none; /* Firefox */
    -ms-user-select: none; /* IE10+/Edge */
    user-select: none; /* Standard */

    padding: 12px;

    white-space: nowrap;
    cursor: pointer;
}


.state:hover {
    background-color: rgba(17, 92, 179, 0.3);
}

.state:last-child {
    border-bottom: 1px rgba(0, 0, 0, 0.3) solid;
}

.state.active {
    background-color: rgba(17, 60, 179, 0.5);
}