T05: CSS Layout

Placing elements on a page used to be painful. Flexbox and Grid changed everything. Think of Flexbox as arranging items in a single line (like books on a shelf), and Grid as organizing items in rows and columns (like a spreadsheet).

Flexbox

Flexbox works in one dimension at a time. Set display: flex on a container, then control how children align and distribute space.

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

.nav-item {
    flex: 1;
}

CSS Grid

Grid works in two dimensions simultaneously. Define rows and columns, then place items into the grid cells.

.layout {
    display: grid;
    grid-template-columns: 250px 1fr;
    grid-template-rows: auto 1fr auto;
    gap: 1rem;
    min-height: 100vh;
}

Responsive Design

Media queries let you apply different styles based on screen size. Mobile-first means writing base styles for small screens and adding complexity for larger ones.

@media (min-width: 768px) {
    .layout { grid-template-columns: 250px 1fr; }
}