.flex {
    display: flex;
}

.h-box {
    flex-direction: row;
}

.v-box {
    flex-direction: column;
}

.fill {
    flex: 1;
    align-self: stretch;
}

.center {
    align-self: center;
}

.center-children {
    justify-content: center;
    align-items: center;
}

.v-center-children {
    align-items: center;
}