.gridded_frame_with_columns {
    display: flex;
    flex-flow: row;
}

.gridded_frame_with_rows {
    display: flex;
    flex-flow: column;
}

.one_of_2_columns {
    width: 50%;
}

.one_of_3_columns {
    width: 33%;
}

.column_with_rows {
    display: flex;
    flex-grow: auto;
    flex-flow: column;
}

.row_with_columns {
    display: flex;
    flex-flow: row;
}

.one_of_2_rows {
    height: 50%;
}