Item
Item[expr_, opts___]represents an item within constructs such Grid
It modifies on outer container applying custom styles specified in opts
Grid[{{Item[a, Frame -> True], b}, {c, d}}]
(*GB[*){{a(*VB[*)(**)(*,*)(*"1:eJxTTMoPSmNkYGAoZgESHvk5KWlMIB47kPAsSc11yq+ACICkg0pzUotZgQy3osTcVLBQSFFpKpoCHiAjuKQos8A/zzOvoLQEoiMxpzgVAMnhGG0="*)(*]VB*)(*|*),(*|*)b}(*||*),(*||*){c(*|*),(*|*)d}}(*]GB*)
Another example
a = {{1, 2}, {3, 4}};
Grid[KroneckerProduct[IdentityMatrix[5], a]] /. {0 -> 0,
x_?NumberQ -> Item[x, Background -> Orange]}
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Options
The same as for Style