The outer gray box has a fixed width and height. The inner blue box is centered using
flex items-center justify-center
on the parent.
flex
: Enables flexbox layout.
items-center
: Vertically aligns items to the center (cross-axis).
justify-center
: Horizontally aligns items to the center (main-axis).
w-64 h-64
: Defines the parent's dimensions, crucial for vertical centering.