body {
    margin: 0;
    font-family: Verdana, sans-serif;
}
#topBar {
    width: 100vw;
    height: 40px;
    margin: 0;
    padding: 0;
    background-color: slategray;
    align-content: center;
    text-align: center;
    color: whitesmoke;
}
#mainContent {
    position: relative;
    width: 100vw;
    height: calc(100vh - 40px);
    margin: 0;
    padding: 0;
}
#leftPanel {
    display: inline-block;
    position: absolute;
    width: 400px;
    padding-right: 4px;
    height: 100%;
    left: 0;
    background-color: #ff000055;
    text-align: center;
}
#leftPanel::after {
    content: '';
    background-color: #ccc;
    position: absolute;
    right: 0;
    width: 4px;
    height: 100%;
    cursor: ew-resize;
}
#centerPanel {
    display: inline-block;
    height: 100%;
    align-content: center;
    text-align: center;
    overflow: hidden;
}
#rightPanel {
    display: inline-block;
    position: absolute;
    width: 400px;
    padding-left: 4px;
    height: 100%;
    right: 0;
    background-color: #00ff0055;
    text-align: center;
}
#rightPanel::after {
    content: '';
    background-color: #ccc;
    position: absolute;
    left: 0;
    width: 4px;
    height: 100%;
    cursor: ew-resize;
}