* {
    box-sizing: border-box;
}

html {
    background-color: #444;
    color: #FFF;
    padding: 0;
    margin: 0;
}

body {
    position: fixed;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;

    display: flex;
    flex-direction: column;

    padding: 0;
    margin: 0;

    font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
}

.panel.top {
    display: block;
    width: 100%;
    height: 4rem;
    border-bottom: 1px solid white;
}

.panel.center {
    display: block;
    width: 100%;
    overflow-y: scroll;
    flex: 1;
}

.panel.bottom {
    width: 100%;
    height: 4rem;
    border-top: 1px solid white;
}

.panel.header {
    text-align: center;
    font-weight: bold;
    font-size: 2rem;
    line-height: 4rem;
    background-color: cornflowerblue;
}

.panel.padded {
    padding: 1rem;
}