---
layout: docs
title: Sizing and positioning
group: utilities
---
## Fixed positioning
The `.pos-f-t` class can be used to easily position elements at the top of the viewport and make them as wide as the viewport. **Be sure you understand the ramifications of fixed-position elements within your project.** Here's how the class is defined:
{% highlight scss %}
.pos-f-t {
position: fixed;
top: 0;
right: 0;
left: 0;
z-index: $zindex-navbar-fixed;
}
{% endhighlight %}
## Width and height
Easily make an element as wide or as tall (relative to its parent) wit our width and height utilities. Includes support for `25%`, `50%`, `75%`, and `100%`.
{% example html %}
Width 25%
Width 50%
Width 75%
Width 100%
{% endexample %}
{% example html %}
Height 25%
Height 50%
Height 75%
Height 100%
{% endexample %}
You can also use `max-width: 100%;` and `max-height: 100%;` utilities as needed.
{% example html %}
![Max-width 100%]()
{% endexample %}
{% example html %}
{% endexample %}