body {
    background: whitesmoke;
}

.column {
    float: left;
    width: 33.3%;
    padding: 4px;
}

.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
    top: -2px;
    left: 2px;
}

.btn {
    margin-bottom: 2px;
}

.panelClose {
    position: absolute;
    visibility: collapse;
}

.panel {
    visibility: visible;
    position: absolute;
    background-color: white;
    border-style: solid;
    border-radius: 10px;
    border-color: cornflowerblue;
    border-radius: 10px;
    top: 40px;
    margin: auto;
    width: 300px;
    padding: 4px;
    margin-left: 40px;
    animation-name: example;
    animation-duration: 1s;
}

.panel-header {
    background-color: cornflowerblue;
    height: 28px;
    border-top-left-radius: 5px;
    border-top-right-radius: 5px;
    color: white;
}

@keyframes example {
    from {
        top: 1px;
        opacity: 0.1
    }

    to {
        top: 40px;
        opacity: 1
    }
}