How Does Vertical Alignment Work with the `vertical-align` Property?

Vertical Alignment with the vertical-align Property

In the world of web design, vertical alignment plays a crucial role in enhancing visual aesthetics and organizing content effectively. The CSS vertical-align property offers a means to vertically position inline elements within a parent element, allowing developers to achieve precise alignment. However, understanding its intricacies can be a perplexing task.

Determining Vertical Alignment

To grasp the mechanisms of vertical-align, we must first acknowledge that it only applies to inline elements. These elements, such as , , or text within block-level elements, occupy a single line and have no implicit height. Additionally, specifying a line-height for elements lacking an inherent one is essential.

The height property of the parent element must possess a static value for vertical alignment to take effect. Auto or percentage values will not suffice. Moreover, various modern browsers encounter difficulties rendering vertical alignment accurately on non-inline elements.

Element Selection for Alignment

A common misconception is that vertical-align is applied to the container element, akin to text-align. However, it should be assigned to the element that requires vertical positioning. For instance, if we wish to center an

tag within a

, the vertical-align property should be applied directly to the

.

Practical Example

Consider the following HTML and CSS code:

HTML:

<div>
<p>CSS:</p>
<pre class="brush:php;toolbar:false">#outer {
  height: 200px;
  text-align: center;
}

#inner {
  display: inline-block;
  height: 200px;
  vertical-align: middle;
}

#header {
  display: inline-block;
}

Intuitively, one might expect the

element to be centered vertically within the

elements. However, this is not the case. To understand why, it's crucial to remember that vertical alignment occurs on a line-by-line basis within the parent element. Therefore, if the content of the

element exceeds a single line, the

will not align as expected.

To illustrate this concept, we can modify the HTML code:

<div>
<p>As you can see, the </p>
<h1 id="element-is-now-centered-vertically-within-the-parent-element-as-vertical-alignment-is-based-on-the-line-height-of-the-text"> element is now centered vertically within the parent element, as vertical alignment is based on the line height of the text.</h1>
</div>