html {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    overflow: hidden;
}
body {
    border: solid black 10px;
    margin: 0px;
    background-color: black;
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
}
.vpane {
    display: flex;
    flex-direction: column;
    justify-content: stretch;
}
.hpane {
    display: flex;
    flex-direction: row;
    justify-content: stretch;
}
.toplevel {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
}
.hterminal {
    flex: 1 1 0;
    min-width: 10px;
    min-height: 10px;
    border: solid grey 1px;
    padding: 2px;
}