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✅ What is the difference between align-items and justify-content in Flexbox? (With Code)

In Flexbox, justify-content and align-items control how flex items are positioned, but each works on a different axis.

🔹 1. justify-content — Aligns items on the main axis

It controls how items are spaced horizontally when flex-direction: row (default).

Example:

<div class="container">
  <div class="box">A</div>
  <div class="box">B</div>
  <div class="box">C</div>
</div>

<style>
.container {
  display: flex;
  justify-content: center; /* main axis */
}
.box {
  padding: 20px;
  background: #90caf9;
  margin: 5px;
}
</style>

➡ This moves items left, center, right, or distributes space evenly.

🔹 2. align-items — Aligns items on the cross axis

It controls how items align vertically when flex-direction: row.

Example:

<div class="container">
  <div class="box">A</div>
  <div class="box tall">B</div>
  <div class="box">C</div>
</div>

<style>
.container {
  display: flex;
  align-items: center; /* cross axis */
}
.box {
  padding: 20px;
  background: #a5d6a7;
  margin: 5px;
}
.tall {
  height: 80px;
}
</style>

➡ This aligns items top, center, bottom, or stretches them vertically.

⭐ Simple Difference (Easy to Remember)