Width and centering · ⁨Chiều rộng và căn giữa⁩

Width

• By default, a block box is as wide as the page.
• width: 300px; makes it a fixed width instead.
• max-width: 600px; is gentler — at most this wide, but shrink on small screens.

Centering a box

• To center a box (not just its text), give it a width, then margin: 0 auto;.
• 0 auto means no top/bottom margin, and equal left/right margins.
• Equal side margins push the box into the middle.

<style>
  .card {
    width: 280px;
    margin: 0 auto;
    padding: 16px;
    background-color: #eef;
  }
</style>
<div class="card">A centered card.</div>

Common mistakes

• Centre a block with a set width using margin: 0 auto.
• A width in % is relative to the parent element.

Now you try

• A box needs a width before margin: 0 auto; can center it.
• Set a width, then center the card.