app.less

html, body, body > * {
    margin: 0;
    width: 100%;
    height: 100%;
}

.flex-horiz {
    display: flex;
    flex-direction: row;
    height: 100%;
}

.flex-vert {
    display: flex;
    flex-direction: column;
    height: 100%;
}


.flex-horiz > *, .flex-vert > * {
    flex-grow: 1;
    flex-shrink: 1;
    flex-basis: 1px;
}

.flex-horiz .flex-shrink, .flex-vert .flex-shrink {
    flex-grow: 0;
    flex-shrink: 1;
}

.flex-horiz .flex-grow, .flex-vert .flex-grow {
    flex-grow: 1;
    flex-shrink: 0;
}