This div uses the Tailwind class `bg-gray-100` to set a light gray background. This is often used for main content areas, cards, or to differentiate sections.
This div uses `bg-blue-600` for a vibrant blue background. Note how `text-white` is used for better contrast on a dark background.
This card uses a very light shade, `bg-emerald-50`, for a subtle background color. The border `border-emerald-200` complements it.
Solid background colors are applied using `bg-{color}-{shade}` utility classes.