CSSjustify-content căn chỉnh theo main axis (mặc định horizontal): flex-start, center, flex-end, space-between, space-around, space-evenly. align-items căn theo cross axis (mặc định vertical): stretch, center, flex-start, flex-end, baseline.
justify-content aligns along the main axis (horizontal by default): flex-start, center, flex-end, space-between, space-around, space-evenly. align-items aligns along the cross axis (vertical by default): stretch, center, flex-start, flex-end, baseline.