confused with center

• main things
  • justify-center: Centers content horizontally (main axis).
  • items-center: Centers content vertically (cross axis).
• others
  • align-content: center
  • content-center: Centers content along the cross axis in multi-line containers.
    • controls `align-content: center;
    • only affects flex containers with wrapping enabled (flex-wrap) and multiple rows of content