CSS Flexbox

Flexbox is a layout model that makes aligning and distributing elements in a row or column straightforward. In the DevBlog you’ll use it everywhere: navigation, cards, header, footer.

Enabling Flexbox

.container {
  display: flex;
}

That’s all it takes for child elements to line up in a row.

Container properties

flex-direction — axis direction

.container {
  display: flex;
  flex-direction: row;            /* default: left to right */
  /* flex-direction: row-reverse;    right to left */
  /* flex-direction: column;         top to bottom */
  /* flex-direction: column-reverse; bottom to top */
}

justify-content — alignment along the main axis

The main axis follows the flex-direction (horizontal by default).

.container {
  justify-content: flex-start;    /* default: push to the left */
  /* justify-content: flex-end;      push to the right */
  /* justify-content: center;        center horizontally */
  /* justify-content: space-between; ends at edges, rest evenly spaced */
  /* justify-content: space-around;  equal space around each item */
  /* justify-content: space-evenly;  strictly equal gaps */
}

align-items — alignment along the cross axis

The cross axis is perpendicular to the main axis (vertical by default).

.container {
  align-items: stretch;     /* default: stretch to container height */
  /* align-items: flex-start; align to top */
  /* align-items: flex-end;   align to bottom */
  /* align-items: center;     center vertically */
  /* align-items: baseline;   align text baselines */
}

gap — spacing between items

.container {
  display: flex;
  gap: 16px;           /* same gap on both axes */
  /* gap: 16px 24px;   vertical | horizontal */
}

Replaces the old approach of adding margin to each child.

flex-wrap — wrap to the next line

.cards-grid {
  display: flex;
  flex-wrap: wrap;         /* wrap items if they don't fit */
  /* flex-wrap: nowrap;    default: all on one line */
  gap: 24px;
}

Item properties

flex — how an item grows and shrinks

Shorthand for flex-grow flex-shrink flex-basis.

.sidebar {
  flex: 0 0 280px;   /* don't grow, don't shrink, fixed 280px */
}

.main-content {
  flex: 1;           /* fill remaining space */
}

order — display order

.featured-post {
  order: -1;   /* show first regardless of HTML order */
}

align-self — alignment for a specific item

.cta-button {
  align-self: flex-end;   /* push to the bottom of the container */
}

DevBlog: navigation bar

<header class="site-header">
  <a href="/" class="logo">DevBlog</a>
  <nav class="site-nav">
    <a href="/" class="nav-link">Home</a>
    <a href="/articles/" class="nav-link">Articles</a>
    <a href="/about/" class="nav-link">About</a>
  </nav>
</header>

.site-header {
  display: flex;
  justify-content: space-between;  /* logo left, nav right */
  align-items: center;
  padding: 0 24px;
  height: 56px;
  border-bottom: 1px solid #e5e7eb;
}

.logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: #111827;
  text-decoration: none;
}

.site-nav {
  display: flex;
  gap: 24px;
}

.nav-link {
  color: #374151;
  text-decoration: none;
  font-weight: 500;
}

DevBlog: wrapping card row

<section class="posts-grid">
  <article class="post-card">...</article>
  <article class="post-card">...</article>
  <article class="post-card">...</article>
</section>

.posts-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
}

.post-card {
  flex: 1 1 300px;    /* minimum 300px wide, can grow */
  max-width: 400px;
  padding: 24px;
  border: 1px solid #e5e7eb;
  border-radius: 8px;
}

On a wide screen — 3 cards per row. On a narrow screen — each card takes the full width.

DevBlog: two-column article layout

<div class="article-layout">
  <main class="article-content">...</main>
  <aside class="article-sidebar">...</aside>
</div>

.article-layout {
  display: flex;
  gap: 48px;
  align-items: flex-start;   /* don't stretch columns to full height */
  max-width: 1100px;
  margin: 0 auto;
  padding: 40px 24px;
}

.article-content {
  flex: 1;           /* fill remaining space */
  min-width: 0;      /* allow shrinking — important in flex! */
}

.article-sidebar {
  flex: 0 0 260px;   /* fixed 260px width */
}

Quick reference