How Can You Achieve Conditional Styling in CSS?

Conditional Styling in CSS: Exploring Alternatives

Traditionally, if/else conditions are not natively supported in CSS. However, there are various approaches to achieve conditional styling.

CSS Classes

One method involves using CSS classes to define different styles for different conditions. For example, you could create two classes:

<p class="normal">Text</p>
<p class="active">Text</p>

And in your CSS file:

p.normal {
  background-position: 150px 8px;
}
p.active {
  background-position: 4px 8px;
}

This approach is widely supported and allows for runtime evaluation of conditions.

CSS Preprocessors

CSS preprocessors such as Sass provide conditional statements that allow you to write code like:

$type: monster;
p {
  @if $type == ocean {
    color: blue;
  } @else if $type == matador {
    color: red;
  } @else if $type == monster {
    color: green;
  } @else {
    color: black;
  }
}

While this provides greater flexibility, it requires pre-processing, which can impact performance.

Custom Properties (CSS Variables)

Custom properties, supported in modern browsers, allow for run-time evaluation of conditions. You could define a custom property like:

:root {
  --main-bg-color: brown;
}

And then use it in your CSS:

.one {
  background-color: var(--main-bg-color);
}
.two {
  background-color: black;
}

Server-side Preprocessing

Server-side preprocessors can generate conditional CSS based on dynamic values. For example, you could write code like:

p {
  background-position: <?php echo (@$_GET['foo'] == 'bar')? "150" : "4"; ?>px 8px;
}

However, this approach can have performance implications due to the need for server-side rendering.

Pure CSS Techniques

Finally, Ahmad Shadeed's article demonstrates various pure CSS techniques for addressing conditional UI scenarios without relying on external mechanisms.

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