From cde26a523402bd0ae7c7996805dc5e6597823359 Mon Sep 17 00:00:00 2001
From: Mark Otto <markdotto@gmail.com>
Date: Tue, 16 Feb 2016 20:21:27 -0800
Subject: [PATCH 1/2] Fixes #19221: Add .w-100 as width: 100% utility class

---
 scss/utilities/_spacing.scss | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/scss/utilities/_spacing.scss b/scss/utilities/_spacing.scss
index cd543c8c90..b7ff044b6d 100644
--- a/scss/utilities/_spacing.scss
+++ b/scss/utilities/_spacing.scss
@@ -1,3 +1,7 @@
+// Width
+
+.w-100 { width: 100% !important; }
+
 // Margin and Padding
 
 .m-x-auto {

From 3165835a1bcfcc3b2046d883bf90e21ab3784c76 Mon Sep 17 00:00:00 2001
From: Chris Rebert <code@chrisrebert.com>
Date: Wed, 6 Apr 2016 15:06:23 -0700
Subject: [PATCH 2/2] Add docs for .w-100 utility class

[skip sauce]
---
 docs/components/utilities.md | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/docs/components/utilities.md b/docs/components/utilities.md
index 76bf5f9bed..829ee49078 100644
--- a/docs/components/utilities.md
+++ b/docs/components/utilities.md
@@ -165,6 +165,14 @@ Sometimes contextual classes cannot be applied due to the specificity of another
 {% capture callout-include %}{% include callout-warning-color-assistive-technologies.md %}{% endcapture %}
 {{ callout-include | markdownify }}
 
+## Widths
+
+Easily make an element as wide as its parent using the `.w-100` utility class, which sets `width: 100%`.
+
+{% example html %}
+<img class="w-100" data-src="holder.js/200px100?outline=yes&text=Width%20%3D%20100%25" alt="Width = 100%">
+{% endexample %}
+
 ## Close icon
 
 Use a generic close icon for dismissing content like modals and alerts. **Be sure to include text for screen readers**, as we've done with `aria-label`.