Grid gives you rows and columns together. Define the tracks, subtract the gaps, and then decide which items span more than one track. Equal fractions share the available width, but intrinsic content can still force a track wider than you expect. minmax with a zero minimum lets a content column shrink within the layout. You'll build equal cards, a full-width header, and a fixed sidebar beside flexible content. The final task changes the track count at a phone breakpoint. Keep the source order meaningful so the same content reads naturally when three columns become one.