Gotcha: Implicit vs. Explicit Base Column Count

This example addresses the "Gotcha" about forgetting or omitting the base case for the smallest screens.

1. Implicit Base Case (Potentially Less Clear)

Below, grid-cols-1 (or any base grid-cols-* ) is omitted. Tailwind's mobile-first nature means it defaults to a single column flow for child `div` elements within a `grid` container if no other column definition matches. While it works, it's less explicit.

Item A

Item B

Item C

Item D

(Code: <div class="grid sm:grid-cols-2 md:grid-cols-4">...</div> ) - On XS screens, items stack, but grid-cols-1 is not explicitly stated.

2. Explicit Base Case (Clearer and Recommended)

Below, grid-cols-1 is explicitly defined for the smallest screens. This makes the intended layout behavior at all screen sizes perfectly clear.

Item 1

Item 2

Item 3

Item 4

(Code: <div class="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-4">...</div> ) - Clear declaration for all screen sizes.

Gotcha Summary:

While Tailwind CSS is mobile-first, and omitting a base grid-cols-* utility might result in a single-column layout on small screens (due to default block behavior of child elements or other implicit grid flow rules), explicitly setting the base case (e.g., grid-cols-1 ) is a best practice. It improves code readability and ensures your intended layout is unambiguous for the smallest viewports.