CSS Grid vs Flexbox: When to Use Each (With Real Examples)

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.container {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
}

.card {
    display: flex;
    flex-direction: column;
}
.card-body {
    flex: 1; /* grows to fill available space */
}
.card-button {
    margin-top: auto; /* pins to bottom */
}

.page {
    display: grid;
    grid-template-columns: 240px 1fr;
    grid-template-rows: 64px 1fr auto;
    grid-template-areas:
        "sidebar header"
        "sidebar main"
        "sidebar footer";
    min-height: 100vh;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.hero {
    display: grid;
}
.hero-image,
.hero-text {
    grid-column: 1;
    grid-row: 1;
}

Does the layout have both rows AND columns?
├── YES → Grid
└── NO (just one axis)
    ├── Is it a single item to be centered?
    │   └── Either works, Flexbox is simpler
    ├── Do children need to wrap to new lines?
    │   ├── YES and they need to align across rows? → Grid
    │   └── YES but rows are independent? → Flexbox with wrap
    └── Is it a simple row/column of items? → Flexbox

/* ❌ Don't do this */
.cards {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}
.card {
    flex: 0 0 calc(33.333% - 1rem);
}

/* ✅ Do this */
.cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1rem;
}

/* ❌ Overkill */
.header {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
}

/* ✅ Clear intent */
.header {
    display: flex;
    align-items: center;
    gap: 1rem;
}

/* Outer structure: Grid */
.layout {
    display: grid;
    grid-template-columns: 240px 1fr;
}

/* Inner content: Flexbox */
.sidebar {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(280px, 100%), 1fr));
}

@container (min-width: 600px) {
    .card {
        grid-template-columns: auto 1fr;
    }
}