{% endexample %}
## Text transform
Transform text in components with text capitalization classes.
{% example html %}
Lowercased text.
Uppercased text.
Capitalized text.
{% endexample %}
## Contextual colors and backgrounds
Convey meaning through color with a handful of emphasis utility classes. These may also be applied to links and will darken on hover just like our default link styles.
{% example html %}
Fusce dapibus, tellus ac cursus commodo, tortor mauris nibh.
Nullam id dolor id nibh ultricies vehicula ut id elit.
Duis mollis, est non commodo luctus, nisi erat porttitor ligula.
Maecenas sed diam eget risus varius blandit sit amet non magna.
Etiam porta sem malesuada magna mollis euismod.
Donec ullamcorper nulla non metus auctor fringilla.
{% endexample %}
Similar to the contextual text color classes, easily set the background of an element to any contextual class. Anchor components will darken on hover, just like the text classes.
{% example html %}
Nullam id dolor id nibh ultricies vehicula ut id elit.
Duis mollis, est non commodo luctus, nisi erat porttitor ligula.
Maecenas sed diam eget risus varius blandit sit amet non magna.
Etiam porta sem malesuada magna mollis euismod.
Donec ullamcorper nulla non metus auctor fringilla.
Cras mattis consectetur purus sit amet fermentum.
{% endexample %}
{% callout info %}
#### Dealing with specificity
Sometimes contextual classes cannot be applied due to the specificity of another selector. In some cases, a sufficient workaround is to wrap your element's content in a `
` with the class.
{% endcallout %}
{% callout warning %}
#### Conveying meaning to assistive technologies
Ensure that any meaning conveyed through color is also conveyed in a format that is not purely presentational.
{% endcallout %}
## Close icon
Use a generic close icon for dismissing content like modals and alerts. **Be sure to include screen reader text when you can** as we've done with `.sr-only`.
{% example html %}
{% endexample %}
## Floats
Float an element to the left or right with a class. `!important` is included to avoid specificity issues. Classes can also be used as mixins.
{% example html %}
Float left
Float right
{% endexample %}
{% highlight scss %}
// Classes
.pull-left {
float: left !important;
}
.pull-right {
float: right !important;
}
// Usage as mixins
.element {
@include pull-left;
}
.another-element {
@include pull-right;
}
{% endhighlight %}
## Center content
Set an element to `display: block;` and center via `margin`. Available as a mixin and class.
{% example html %}
Centered block
{% endexample %}
{% highlight scss %}
// Class
.center-block {
display: block;
margin-left: auto;
margin-right: auto;
}
// Usage as a mixin
.element {
@include center-block;
}
{% endhighlight %}
Easily clear `float`s by adding `.clearfix` **to the parent element**. Utilizes [the micro clearfix](http://nicolasgallagher.com/micro-clearfix-hack/) as popularized by Nicolas Gallagher. Can also be used as a mixin.
{% highlight html %}
...
{% endhighlight %}
{% highlight scss %}
// Mixin itself
.clearfix() {
&:before,
&:after {
content: " ";
display: table;
}
&:after {
clear: both;
}
}
// Usage as a mixin
.element {
@include clearfix;
}
{% endhighlight %}
## Hidden content
Hide any HTML element with the `[hidden]` attribute. Previously, v3.x included a `.hidden` class that forced toggled content. However, we removed it due to conflicts with jQuery's `hide()` function. It's taken from [PureCSS](http://purecss.io). While `[hidden]` isn't natively supported by IE9-10, declaring it `display: none` in our CSS gets around that problem.
Furthermore, `.invisible` can be used to toggle the visibility of an element, meaning its `display` is not modified and the element can still affect the flow of the document.
{% highlight html %}
{% endhighlight %}
## Invisible content
The `.invisible` class can be used to toggle only the visibility of an element, meaning its `display` is not modified and the element can still affect the flow of the document.
{% highlight html %}
...
{% endhighlight %}
{% highlight scss %}
// Class
.invisible {
visibility: hidden;
}
// Usage as a mixin
.element {
.invisible();
}
{% endhighlight %}
## Screen readers
Hide an element to all devices **except screen readers** with `.sr-only`. Combine `.sr-only` with `.sr-only-focusable` to show the element again when it's focused (e.g. by a keyboard-only user). Can also be used as mixins.
{% comment %}
Necessary for following [accessibility best practices](../getting-started/#accessibility).
{% endcomment %}
{% highlight html %}
Skip to main content
{% endhighlight %}
{% highlight scss %}
// Usage as a mixin
.skip-navigation {
@include sr-only;
@include sr-only-focusable;
}
{% endhighlight %}
## Image replacement
Utilize the `.text-hide` class or mixin to help replace an element's text content with a background image.
{% highlight html %}
Custom heading
{% endhighlight %}
{% highlight scss %}
// Usage as a mixin
.heading {
@include text-hide;
}
{% endhighlight %}
## Responsive embeds
Allow browsers to determine video or slideshow dimensions based on the width of their containing block by creating an intrinsic ratio that will properly scale on any device.
Rules are directly applied to `
{% endexample %}
Aspect ratios can be customized with modifier classes.
{% highlight html %}