diff --git a/docs/4.0/examples/album/index.html b/docs/4.0/examples/album/index.html
index 6723e53fb..ecd3f3517 100644
--- a/docs/4.0/examples/album/index.html
+++ b/docs/4.0/examples/album/index.html
@@ -18,90 +18,96 @@
 
   <body>
 
-    <div class="collapse bg-dark" id="navbarHeader">
-      <div class="container">
-        <div class="row">
-          <div class="col-sm-8 py-4">
-            <h4 class="text-white">About</h4>
-            <p class="text-muted">Add some information about the album below, the author, or any other background context. Make it a few sentences long so folks can pick up some informative tidbits. Then, link them off to some social networking sites or contact information.</p>
-          </div>
-          <div class="col-sm-4 py-4">
-            <h4 class="text-white">Contact</h4>
-            <ul class="list-unstyled">
-              <li><a href="#" class="text-white">Follow on Twitter</a></li>
-              <li><a href="#" class="text-white">Like on Facebook</a></li>
-              <li><a href="#" class="text-white">Email me</a></li>
-            </ul>
+    <header>
+      <div class="collapse bg-dark" id="navbarHeader">
+        <div class="container">
+          <div class="row">
+            <div class="col-sm-8 py-4">
+              <h4 class="text-white">About</h4>
+              <p class="text-muted">Add some information about the album below, the author, or any other background context. Make it a few sentences long so folks can pick up some informative tidbits. Then, link them off to some social networking sites or contact information.</p>
+            </div>
+            <div class="col-sm-4 py-4">
+              <h4 class="text-white">Contact</h4>
+              <ul class="list-unstyled">
+                <li><a href="#" class="text-white">Follow on Twitter</a></li>
+                <li><a href="#" class="text-white">Like on Facebook</a></li>
+                <li><a href="#" class="text-white">Email me</a></li>
+              </ul>
+            </div>
           </div>
         </div>
       </div>
-    </div>
-    <div class="navbar navbar-dark bg-dark">
-      <div class="container d-flex justify-content-between">
-        <a href="#" class="navbar-brand">Album</a>
-        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarHeader" aria-controls="navbarHeader" aria-expanded="false" aria-label="Toggle navigation">
-          <span class="navbar-toggler-icon"></span>
-        </button>
-      </div>
-    </div>
-
-    <section class="jumbotron text-center">
-      <div class="container">
-        <h1 class="jumbotron-heading">Album example</h1>
-        <p class="lead text-muted">Something short and leading about the collection below—its contents, the creator, etc. Make it short and sweet, but not too short so folks don't simply skip over it entirely.</p>
-        <p>
-          <a href="#" class="btn btn-primary">Main call to action</a>
-          <a href="#" class="btn btn-secondary">Secondary action</a>
-        </p>
-      </div>
-    </section>
-
-    <div class="album text-muted">
-      <div class="container">
-
-        <div class="row">
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
-
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
-
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
-          <div class="card">
-            <img data-src="holder.js/100px280/thumb" alt="Card image cap">
-            <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
-          </div>
+      <div class="navbar navbar-dark bg-dark">
+        <div class="container d-flex justify-content-between">
+          <a href="#" class="navbar-brand">Album</a>
+          <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarHeader" aria-controls="navbarHeader" aria-expanded="false" aria-label="Toggle navigation">
+            <span class="navbar-toggler-icon"></span>
+          </button>
         </div>
-
       </div>
-    </div>
+    </header>
+
+    <main role="main">
+
+      <section class="jumbotron text-center">
+        <div class="container">
+          <h1 class="jumbotron-heading">Album example</h1>
+          <p class="lead text-muted">Something short and leading about the collection below—its contents, the creator, etc. Make it short and sweet, but not too short so folks don't simply skip over it entirely.</p>
+          <p>
+            <a href="#" class="btn btn-primary">Main call to action</a>
+            <a href="#" class="btn btn-secondary">Secondary action</a>
+          </p>
+        </div>
+      </section>
+
+      <div class="album text-muted">
+        <div class="container">
+
+          <div class="row">
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+            <div class="card">
+              <img data-src="holder.js/100px280/thumb" alt="Card image cap">
+              <p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
+            </div>
+          </div>
+
+        </div>
+      </div>
+
+    </main>
 
     <footer class="text-muted">
       <div class="container">
diff --git a/docs/4.0/examples/blog/index.html b/docs/4.0/examples/blog/index.html
index a021d7afa..4601fd76d 100644
--- a/docs/4.0/examples/blog/index.html
+++ b/docs/4.0/examples/blog/index.html
@@ -18,26 +18,28 @@
 
   <body>
 
-    <div class="blog-masthead">
-      <div class="container">
-        <nav class="nav">
-          <a class="nav-link active" href="#">Home</a>
-          <a class="nav-link" href="#">New features</a>
-          <a class="nav-link" href="#">Press</a>
-          <a class="nav-link" href="#">New hires</a>
-          <a class="nav-link" href="#">About</a>
-        </nav>
+    <header>
+      <div class="blog-masthead">
+        <div class="container">
+          <nav class="nav">
+            <a class="nav-link active" href="#">Home</a>
+            <a class="nav-link" href="#">New features</a>
+            <a class="nav-link" href="#">Press</a>
+            <a class="nav-link" href="#">New hires</a>
+            <a class="nav-link" href="#">About</a>
+          </nav>
+        </div>
       </div>
-    </div>
 
-    <div class="blog-header">
-      <div class="container">
-        <h1 class="blog-title">The Bootstrap Blog</h1>
-        <p class="lead blog-description">An example blog template built with Bootstrap.</p>
+      <div class="blog-header">
+        <div class="container">
+          <h1 class="blog-title">The Bootstrap Blog</h1>
+          <p class="lead blog-description">An example blog template built with Bootstrap.</p>
+        </div>
       </div>
-    </div>
+    </header>
 
-    <div class="container">
+    <main role="main" class="container">
 
       <div class="row">
 
@@ -109,7 +111,7 @@
 
         </div><!-- /.blog-main -->
 
-        <div class="col-sm-3 ml-sm-auto blog-sidebar">
+        <aside class="col-sm-3 ml-sm-auto blog-sidebar">
           <div class="sidebar-module sidebar-module-inset">
             <h4>About</h4>
             <p>Etiam porta <em>sem malesuada magna</em> mollis euismod. Cras mattis consectetur purus sit amet fermentum. Aenean lacinia bibendum nulla sed consectetur.</p>
@@ -139,11 +141,11 @@
               <li><a href="#">Facebook</a></li>
             </ol>
           </div>
-        </div><!-- /.blog-sidebar -->
+        </aside><!-- /.blog-sidebar -->
 
       </div><!-- /.row -->
 
-    </div><!-- /.container -->
+    </main><!-- /.container -->
 
     <footer class="blog-footer">
       <p>Blog template built for <a href="https://getbootstrap.com">Bootstrap</a> by <a href="https://twitter.com/mdo">@mdo</a>.</p>
diff --git a/docs/4.0/examples/carousel/index.html b/docs/4.0/examples/carousel/index.html
index 7d4a6ea22..fdaebb350 100644
--- a/docs/4.0/examples/carousel/index.html
+++ b/docs/4.0/examples/carousel/index.html
@@ -17,158 +17,164 @@
   </head>
   <body>
 
-    <nav class="navbar navbar-expand-md navbar-dark fixed-top bg-dark">
-      <a class="navbar-brand" href="#">Carousel</a>
-      <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
-        <span class="navbar-toggler-icon"></span>
-      </button>
-      <div class="collapse navbar-collapse" id="navbarCollapse">
-        <ul class="navbar-nav mr-auto">
-          <li class="nav-item active">
-            <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
-          </li>
-          <li class="nav-item">
-            <a class="nav-link" href="#">Link</a>
-          </li>
-          <li class="nav-item">
-            <a class="nav-link disabled" href="#">Disabled</a>
-          </li>
-        </ul>
-        <form class="form-inline mt-2 mt-md-0">
-          <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
-          <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
-        </form>
-      </div>
-    </nav>
+    <header>
+      <nav class="navbar navbar-expand-md navbar-dark fixed-top bg-dark">
+        <a class="navbar-brand" href="#">Carousel</a>
+        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
+          <span class="navbar-toggler-icon"></span>
+        </button>
+        <div class="collapse navbar-collapse" id="navbarCollapse">
+          <ul class="navbar-nav mr-auto">
+            <li class="nav-item active">
+              <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
+            </li>
+            <li class="nav-item">
+              <a class="nav-link" href="#">Link</a>
+            </li>
+            <li class="nav-item">
+              <a class="nav-link disabled" href="#">Disabled</a>
+            </li>
+          </ul>
+          <form class="form-inline mt-2 mt-md-0">
+            <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
+            <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
+          </form>
+        </div>
+      </nav>
+    </header>
 
-    <div id="myCarousel" class="carousel slide" data-ride="carousel">
-      <ol class="carousel-indicators">
-        <li data-target="#myCarousel" data-slide-to="0" class="active"></li>
-        <li data-target="#myCarousel" data-slide-to="1"></li>
-        <li data-target="#myCarousel" data-slide-to="2"></li>
-      </ol>
-      <div class="carousel-inner">
-        <div class="carousel-item active">
-          <img class="first-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="First slide">
-          <div class="container">
-            <div class="carousel-caption text-left">
-              <h1>Example headline.</h1>
-              <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
-              <p><a class="btn btn-lg btn-primary" href="#" role="button">Sign up today</a></p>
+    <main role="main">
+
+      <div id="myCarousel" class="carousel slide" data-ride="carousel">
+        <ol class="carousel-indicators">
+          <li data-target="#myCarousel" data-slide-to="0" class="active"></li>
+          <li data-target="#myCarousel" data-slide-to="1"></li>
+          <li data-target="#myCarousel" data-slide-to="2"></li>
+        </ol>
+        <div class="carousel-inner">
+          <div class="carousel-item active">
+            <img class="first-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="First slide">
+            <div class="container">
+              <div class="carousel-caption text-left">
+                <h1>Example headline.</h1>
+                <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
+                <p><a class="btn btn-lg btn-primary" href="#" role="button">Sign up today</a></p>
+              </div>
+            </div>
+          </div>
+          <div class="carousel-item">
+            <img class="second-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Second slide">
+            <div class="container">
+              <div class="carousel-caption">
+                <h1>Another example headline.</h1>
+                <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
+                <p><a class="btn btn-lg btn-primary" href="#" role="button">Learn more</a></p>
+              </div>
+            </div>
+          </div>
+          <div class="carousel-item">
+            <img class="third-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Third slide">
+            <div class="container">
+              <div class="carousel-caption text-right">
+                <h1>One more for good measure.</h1>
+                <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
+                <p><a class="btn btn-lg btn-primary" href="#" role="button">Browse gallery</a></p>
+              </div>
             </div>
           </div>
         </div>
-        <div class="carousel-item">
-          <img class="second-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Second slide">
-          <div class="container">
-            <div class="carousel-caption">
-              <h1>Another example headline.</h1>
-              <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
-              <p><a class="btn btn-lg btn-primary" href="#" role="button">Learn more</a></p>
-            </div>
+        <a class="carousel-control-prev" href="#myCarousel" role="button" data-slide="prev">
+          <span class="carousel-control-prev-icon" aria-hidden="true"></span>
+          <span class="sr-only">Previous</span>
+        </a>
+        <a class="carousel-control-next" href="#myCarousel" role="button" data-slide="next">
+          <span class="carousel-control-next-icon" aria-hidden="true"></span>
+          <span class="sr-only">Next</span>
+        </a>
+      </div>
+
+
+      <!-- Marketing messaging and featurettes
+      ================================================== -->
+      <!-- Wrap the rest of the page in another container to center all the content. -->
+
+      <div class="container marketing">
+
+        <!-- Three columns of text below the carousel -->
+        <div class="row">
+          <div class="col-lg-4">
+            <img class="rounded-circle" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Generic placeholder image" width="140" height="140">
+            <h2>Heading</h2>
+            <p>Donec sed odio dui. Etiam porta sem malesuada magna mollis euismod. Nullam id dolor id nibh ultricies vehicula ut id elit. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna.</p>
+            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
+          </div><!-- /.col-lg-4 -->
+          <div class="col-lg-4">
+            <img class="rounded-circle" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Generic placeholder image" width="140" height="140">
+            <h2>Heading</h2>
+            <p>Duis mollis, est non commodo luctus, nisi erat porttitor ligula, eget lacinia odio sem nec elit. Cras mattis consectetur purus sit amet fermentum. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh.</p>
+            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
+          </div><!-- /.col-lg-4 -->
+          <div class="col-lg-4">
+            <img class="rounded-circle" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Generic placeholder image" width="140" height="140">
+            <h2>Heading</h2>
+            <p>Donec sed odio dui. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Vestibulum id ligula porta felis euismod semper. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus.</p>
+            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
+          </div><!-- /.col-lg-4 -->
+        </div><!-- /.row -->
+
+
+        <!-- START THE FEATURETTES -->
+
+        <hr class="featurette-divider">
+
+        <div class="row featurette">
+          <div class="col-md-7">
+            <h2 class="featurette-heading">First featurette heading. <span class="text-muted">It'll blow your mind.</span></h2>
+            <p class="lead">Donec ullamcorper nulla non metus auctor fringilla. Vestibulum id ligula porta felis euismod semper. Praesent commodo cursus magna, vel scelerisque nisl consectetur. Fusce dapibus, tellus ac cursus commodo.</p>
+          </div>
+          <div class="col-md-5">
+            <img class="featurette-image img-fluid mx-auto" data-src="holder.js/500x500/auto" alt="Generic placeholder image">
           </div>
         </div>
-        <div class="carousel-item">
-          <img class="third-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Third slide">
-          <div class="container">
-            <div class="carousel-caption text-right">
-              <h1>One more for good measure.</h1>
-              <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
-              <p><a class="btn btn-lg btn-primary" href="#" role="button">Browse gallery</a></p>
-            </div>
+
+        <hr class="featurette-divider">
+
+        <div class="row featurette">
+          <div class="col-md-7 order-md-2">
+            <h2 class="featurette-heading">Oh yeah, it's that good. <span class="text-muted">See for yourself.</span></h2>
+            <p class="lead">Donec ullamcorper nulla non metus auctor fringilla. Vestibulum id ligula porta felis euismod semper. Praesent commodo cursus magna, vel scelerisque nisl consectetur. Fusce dapibus, tellus ac cursus commodo.</p>
+          </div>
+          <div class="col-md-5 order-md-1">
+            <img class="featurette-image img-fluid mx-auto" data-src="holder.js/500x500/auto" alt="Generic placeholder image">
           </div>
         </div>
-      </div>
-      <a class="carousel-control-prev" href="#myCarousel" role="button" data-slide="prev">
-        <span class="carousel-control-prev-icon" aria-hidden="true"></span>
-        <span class="sr-only">Previous</span>
-      </a>
-      <a class="carousel-control-next" href="#myCarousel" role="button" data-slide="next">
-        <span class="carousel-control-next-icon" aria-hidden="true"></span>
-        <span class="sr-only">Next</span>
-      </a>
-    </div>
 
+        <hr class="featurette-divider">
 
-    <!-- Marketing messaging and featurettes
-    ================================================== -->
-    <!-- Wrap the rest of the page in another container to center all the content. -->
-
-    <div class="container marketing">
-
-      <!-- Three columns of text below the carousel -->
-      <div class="row">
-        <div class="col-lg-4">
-          <img class="rounded-circle" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Generic placeholder image" width="140" height="140">
-          <h2>Heading</h2>
-          <p>Donec sed odio dui. Etiam porta sem malesuada magna mollis euismod. Nullam id dolor id nibh ultricies vehicula ut id elit. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna.</p>
-          <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
-        </div><!-- /.col-lg-4 -->
-        <div class="col-lg-4">
-          <img class="rounded-circle" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Generic placeholder image" width="140" height="140">
-          <h2>Heading</h2>
-          <p>Duis mollis, est non commodo luctus, nisi erat porttitor ligula, eget lacinia odio sem nec elit. Cras mattis consectetur purus sit amet fermentum. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh.</p>
-          <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
-        </div><!-- /.col-lg-4 -->
-        <div class="col-lg-4">
-          <img class="rounded-circle" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Generic placeholder image" width="140" height="140">
-          <h2>Heading</h2>
-          <p>Donec sed odio dui. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Vestibulum id ligula porta felis euismod semper. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus.</p>
-          <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
-        </div><!-- /.col-lg-4 -->
-      </div><!-- /.row -->
-
-
-      <!-- START THE FEATURETTES -->
-
-      <hr class="featurette-divider">
-
-      <div class="row featurette">
-        <div class="col-md-7">
-          <h2 class="featurette-heading">First featurette heading. <span class="text-muted">It'll blow your mind.</span></h2>
-          <p class="lead">Donec ullamcorper nulla non metus auctor fringilla. Vestibulum id ligula porta felis euismod semper. Praesent commodo cursus magna, vel scelerisque nisl consectetur. Fusce dapibus, tellus ac cursus commodo.</p>
+        <div class="row featurette">
+          <div class="col-md-7">
+            <h2 class="featurette-heading">And lastly, this one. <span class="text-muted">Checkmate.</span></h2>
+            <p class="lead">Donec ullamcorper nulla non metus auctor fringilla. Vestibulum id ligula porta felis euismod semper. Praesent commodo cursus magna, vel scelerisque nisl consectetur. Fusce dapibus, tellus ac cursus commodo.</p>
+          </div>
+          <div class="col-md-5">
+            <img class="featurette-image img-fluid mx-auto" data-src="holder.js/500x500/auto" alt="Generic placeholder image">
+          </div>
         </div>
-        <div class="col-md-5">
-          <img class="featurette-image img-fluid mx-auto" data-src="holder.js/500x500/auto" alt="Generic placeholder image">
-        </div>
-      </div>
 
-      <hr class="featurette-divider">
+        <hr class="featurette-divider">
 
-      <div class="row featurette">
-        <div class="col-md-7 order-md-2">
-          <h2 class="featurette-heading">Oh yeah, it's that good. <span class="text-muted">See for yourself.</span></h2>
-          <p class="lead">Donec ullamcorper nulla non metus auctor fringilla. Vestibulum id ligula porta felis euismod semper. Praesent commodo cursus magna, vel scelerisque nisl consectetur. Fusce dapibus, tellus ac cursus commodo.</p>
-        </div>
-        <div class="col-md-5 order-md-1">
-          <img class="featurette-image img-fluid mx-auto" data-src="holder.js/500x500/auto" alt="Generic placeholder image">
-        </div>
-      </div>
+        <!-- /END THE FEATURETTES -->
 
-      <hr class="featurette-divider">
-
-      <div class="row featurette">
-        <div class="col-md-7">
-          <h2 class="featurette-heading">And lastly, this one. <span class="text-muted">Checkmate.</span></h2>
-          <p class="lead">Donec ullamcorper nulla non metus auctor fringilla. Vestibulum id ligula porta felis euismod semper. Praesent commodo cursus magna, vel scelerisque nisl consectetur. Fusce dapibus, tellus ac cursus commodo.</p>
-        </div>
-        <div class="col-md-5">
-          <img class="featurette-image img-fluid mx-auto" data-src="holder.js/500x500/auto" alt="Generic placeholder image">
-        </div>
-      </div>
-
-      <hr class="featurette-divider">
-
-      <!-- /END THE FEATURETTES -->
+      </div><!-- /.container -->
 
 
       <!-- FOOTER -->
-      <footer>
+      <footer class="container">
         <p class="float-right"><a href="#">Back to top</a></p>
         <p>&copy; 2017 Company, Inc. &middot; <a href="#">Privacy</a> &middot; <a href="#">Terms</a></p>
       </footer>
 
-    </div><!-- /.container -->
+    </main>
 
 
     <!-- Bootstrap core JavaScript
diff --git a/docs/4.0/examples/cover/index.html b/docs/4.0/examples/cover/index.html
index bc48f4cd0..07bb7d39b 100644
--- a/docs/4.0/examples/cover/index.html
+++ b/docs/4.0/examples/cover/index.html
@@ -24,7 +24,7 @@
 
         <div class="cover-container">
 
-          <div class="masthead clearfix">
+          <header class="masthead clearfix">
             <div class="inner">
               <h3 class="masthead-brand">Cover</h3>
               <nav class="nav nav-masthead">
@@ -33,21 +33,21 @@
                 <a class="nav-link" href="#">Contact</a>
               </nav>
             </div>
-          </div>
+          </header>
 
-          <div class="inner cover">
+          <main role="main" class="inner cover">
             <h1 class="cover-heading">Cover your page.</h1>
             <p class="lead">Cover is a one-page template for building simple and beautiful home pages. Download, edit the text, and add your own fullscreen background photo to make it your own.</p>
             <p class="lead">
               <a href="#" class="btn btn-lg btn-secondary">Learn more</a>
             </p>
-          </div>
+          </main>
 
-          <div class="mastfoot">
+          <footer class="mastfoot">
             <div class="inner">
               <p>Cover template for <a href="https://getbootstrap.com">Bootstrap</a>, by <a href="https://twitter.com/mdo">@mdo</a>.</p>
             </div>
-          </div>
+          </footer>
 
         </div>
 
diff --git a/docs/4.0/examples/dashboard/index.html b/docs/4.0/examples/dashboard/index.html
index 512564610..a9cf351b1 100644
--- a/docs/4.0/examples/dashboard/index.html
+++ b/docs/4.0/examples/dashboard/index.html
@@ -17,33 +17,35 @@
   </head>
 
   <body>
-    <nav class="navbar navbar-expand-md navbar-dark fixed-top bg-dark">
-      <a class="navbar-brand" href="#">Dashboard</a>
-      <button class="navbar-toggler d-lg-none" type="button" data-toggle="collapse" data-target="#navbarsExampleDefault" aria-controls="navbarsExampleDefault" aria-expanded="false" aria-label="Toggle navigation">
-        <span class="navbar-toggler-icon"></span>
-      </button>
+    <header>
+      <nav class="navbar navbar-expand-md navbar-dark fixed-top bg-dark">
+        <a class="navbar-brand" href="#">Dashboard</a>
+        <button class="navbar-toggler d-lg-none" type="button" data-toggle="collapse" data-target="#navbarsExampleDefault" aria-controls="navbarsExampleDefault" aria-expanded="false" aria-label="Toggle navigation">
+          <span class="navbar-toggler-icon"></span>
+        </button>
 
-      <div class="collapse navbar-collapse" id="navbarsExampleDefault">
-        <ul class="navbar-nav mr-auto">
-          <li class="nav-item active">
-            <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
-          </li>
-          <li class="nav-item">
-            <a class="nav-link" href="#">Settings</a>
-          </li>
-          <li class="nav-item">
-            <a class="nav-link" href="#">Profile</a>
-          </li>
-          <li class="nav-item">
-            <a class="nav-link" href="#">Help</a>
-          </li>
-        </ul>
-        <form class="form-inline mt-2 mt-md-0">
-          <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
-          <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
-        </form>
-      </div>
-    </nav>
+        <div class="collapse navbar-collapse" id="navbarsExampleDefault">
+          <ul class="navbar-nav mr-auto">
+            <li class="nav-item active">
+              <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
+            </li>
+            <li class="nav-item">
+              <a class="nav-link" href="#">Settings</a>
+            </li>
+            <li class="nav-item">
+              <a class="nav-link" href="#">Profile</a>
+            </li>
+            <li class="nav-item">
+              <a class="nav-link" href="#">Help</a>
+            </li>
+          </ul>
+          <form class="form-inline mt-2 mt-md-0">
+            <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
+            <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
+          </form>
+        </div>
+      </nav>
+    </header>
 
     <div class="container-fluid">
       <div class="row">
@@ -91,7 +93,7 @@
           </ul>
         </nav>
 
-        <main class="col-sm-9 ml-sm-auto col-md-10 pt-3" role="main">
+        <main  role="main" class="col-sm-9 ml-sm-auto col-md-10 pt-3">
           <h1>Dashboard</h1>
 
           <section class="row text-center placeholders">
diff --git a/docs/4.0/examples/jumbotron/index.html b/docs/4.0/examples/jumbotron/index.html
index ac0ae3a29..a71a07715 100644
--- a/docs/4.0/examples/jumbotron/index.html
+++ b/docs/4.0/examples/jumbotron/index.html
@@ -51,42 +51,46 @@
       </div>
     </nav>
 
-    <!-- Main jumbotron for a primary marketing message or call to action -->
-    <div class="jumbotron">
+    <main role="main">
+
+      <!-- Main jumbotron for a primary marketing message or call to action -->
+      <div class="jumbotron">
+        <div class="container">
+          <h1 class="display-3">Hello, world!</h1>
+          <p>This is a template for a simple marketing or informational website. It includes a large callout called a jumbotron and three supporting pieces of content. Use it as a starting point to create something more unique.</p>
+          <p><a class="btn btn-primary btn-lg" href="#" role="button">Learn more &raquo;</a></p>
+        </div>
+      </div>
+
       <div class="container">
-        <h1 class="display-3">Hello, world!</h1>
-        <p>This is a template for a simple marketing or informational website. It includes a large callout called a jumbotron and three supporting pieces of content. Use it as a starting point to create something more unique.</p>
-        <p><a class="btn btn-primary btn-lg" href="#" role="button">Learn more &raquo;</a></p>
-      </div>
-    </div>
-
-    <div class="container">
-      <!-- Example row of columns -->
-      <div class="row">
-        <div class="col-md-4">
-          <h2>Heading</h2>
-          <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
-          <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
+        <!-- Example row of columns -->
+        <div class="row">
+          <div class="col-md-4">
+            <h2>Heading</h2>
+            <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
+            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
+          </div>
+          <div class="col-md-4">
+            <h2>Heading</h2>
+            <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
+            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
+          </div>
+          <div class="col-md-4">
+            <h2>Heading</h2>
+            <p>Donec sed odio dui. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Vestibulum id ligula porta felis euismod semper. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus.</p>
+            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
+          </div>
         </div>
-        <div class="col-md-4">
-          <h2>Heading</h2>
-          <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
-          <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
-        </div>
-        <div class="col-md-4">
-          <h2>Heading</h2>
-          <p>Donec sed odio dui. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Vestibulum id ligula porta felis euismod semper. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus.</p>
-          <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
-        </div>
-      </div>
 
-      <hr>
+        <hr>
 
-      <footer>
-        <p>&copy; Company 2017</p>
-      </footer>
-    </div> <!-- /container -->
+      </div> <!-- /container -->
 
+    </main>
+
+    <footer class="container">
+      <p>&copy; Company 2017</p>
+    </footer>
 
     <!-- Bootstrap core JavaScript
     ================================================== -->
diff --git a/docs/4.0/examples/justified-nav/index.html b/docs/4.0/examples/justified-nav/index.html
index 84c241c1d..d478a559c 100644
--- a/docs/4.0/examples/justified-nav/index.html
+++ b/docs/4.0/examples/justified-nav/index.html
@@ -20,7 +20,7 @@
 
     <div class="container">
 
-      <div class="masthead">
+      <header class="masthead">
         <h3 class="text-muted">Project name</h3>
 
         <nav class="navbar navbar-expand-md navbar-light bg-light rounded mb-3">
@@ -55,33 +55,37 @@
             </ul>
           </div>
         </nav>
-      </div>
+      </header>
 
-      <!-- Jumbotron -->
-      <div class="jumbotron">
-        <h1>Marketing stuff!</h1>
-        <p class="lead">Cras justo odio, dapibus ac facilisis in, egestas eget quam. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet.</p>
-        <p><a class="btn btn-lg btn-success" href="#" role="button">Get started today</a></p>
-      </div>
+      <main role="main">
 
-      <!-- Example row of columns -->
-      <div class="row">
-        <div class="col-lg-4">
-          <h2>Heading</h2>
-          <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
-          <p><a class="btn btn-primary" href="#" role="button">View details &raquo;</a></p>
+        <!-- Jumbotron -->
+        <div class="jumbotron">
+          <h1>Marketing stuff!</h1>
+          <p class="lead">Cras justo odio, dapibus ac facilisis in, egestas eget quam. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet.</p>
+          <p><a class="btn btn-lg btn-success" href="#" role="button">Get started today</a></p>
         </div>
-        <div class="col-lg-4">
-          <h2>Heading</h2>
-          <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
-          <p><a class="btn btn-primary" href="#" role="button">View details &raquo;</a></p>
+
+        <!-- Example row of columns -->
+        <div class="row">
+          <div class="col-lg-4">
+            <h2>Heading</h2>
+            <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
+            <p><a class="btn btn-primary" href="#" role="button">View details &raquo;</a></p>
+          </div>
+          <div class="col-lg-4">
+            <h2>Heading</h2>
+            <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
+            <p><a class="btn btn-primary" href="#" role="button">View details &raquo;</a></p>
+          </div>
+          <div class="col-lg-4">
+            <h2>Heading</h2>
+            <p>Donec sed odio dui. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Vestibulum id ligula porta felis euismod semper. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa.</p>
+            <p><a class="btn btn-primary" href="#" role="button">View details &raquo;</a></p>
+          </div>
         </div>
-        <div class="col-lg-4">
-          <h2>Heading</h2>
-          <p>Donec sed odio dui. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Vestibulum id ligula porta felis euismod semper. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa.</p>
-          <p><a class="btn btn-primary" href="#" role="button">View details &raquo;</a></p>
-        </div>
-      </div>
+
+      </main>
 
       <!-- Site footer -->
       <footer class="footer">
diff --git a/docs/4.0/examples/narrow-jumbotron/index.html b/docs/4.0/examples/narrow-jumbotron/index.html
index a1a5d1b64..a23076ea0 100644
--- a/docs/4.0/examples/narrow-jumbotron/index.html
+++ b/docs/4.0/examples/narrow-jumbotron/index.html
@@ -19,7 +19,7 @@
   <body>
 
     <div class="container">
-      <div class="header clearfix">
+      <header class="header clearfix">
         <nav>
           <ul class="nav nav-pills float-right">
             <li class="nav-item">
@@ -34,37 +34,41 @@
           </ul>
         </nav>
         <h3 class="text-muted">Project name</h3>
-      </div>
+      </header>
 
-      <div class="jumbotron">
-        <h1 class="display-3">Jumbotron heading</h1>
-        <p class="lead">Cras justo odio, dapibus ac facilisis in, egestas eget quam. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus.</p>
-        <p><a class="btn btn-lg btn-success" href="#" role="button">Sign up today</a></p>
-      </div>
+      <main role="main">
 
-      <div class="row marketing">
-        <div class="col-lg-6">
-          <h4>Subheading</h4>
-          <p>Donec id elit non mi porta gravida at eget metus. Maecenas faucibus mollis interdum.</p>
-
-          <h4>Subheading</h4>
-          <p>Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Cras mattis consectetur purus sit amet fermentum.</p>
-
-          <h4>Subheading</h4>
-          <p>Maecenas sed diam eget risus varius blandit sit amet non magna.</p>
+        <div class="jumbotron">
+          <h1 class="display-3">Jumbotron heading</h1>
+          <p class="lead">Cras justo odio, dapibus ac facilisis in, egestas eget quam. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus.</p>
+          <p><a class="btn btn-lg btn-success" href="#" role="button">Sign up today</a></p>
         </div>
 
-        <div class="col-lg-6">
-          <h4>Subheading</h4>
-          <p>Donec id elit non mi porta gravida at eget metus. Maecenas faucibus mollis interdum.</p>
+        <div class="row marketing">
+          <div class="col-lg-6">
+            <h4>Subheading</h4>
+            <p>Donec id elit non mi porta gravida at eget metus. Maecenas faucibus mollis interdum.</p>
 
-          <h4>Subheading</h4>
-          <p>Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Cras mattis consectetur purus sit amet fermentum.</p>
+            <h4>Subheading</h4>
+            <p>Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Cras mattis consectetur purus sit amet fermentum.</p>
 
-          <h4>Subheading</h4>
-          <p>Maecenas sed diam eget risus varius blandit sit amet non magna.</p>
+            <h4>Subheading</h4>
+            <p>Maecenas sed diam eget risus varius blandit sit amet non magna.</p>
+          </div>
+
+          <div class="col-lg-6">
+            <h4>Subheading</h4>
+            <p>Donec id elit non mi porta gravida at eget metus. Maecenas faucibus mollis interdum.</p>
+
+            <h4>Subheading</h4>
+            <p>Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Cras mattis consectetur purus sit amet fermentum.</p>
+
+            <h4>Subheading</h4>
+            <p>Maecenas sed diam eget risus varius blandit sit amet non magna.</p>
+          </div>
         </div>
-      </div>
+
+      </main>
 
       <footer class="footer">
         <p>&copy; Company 2017</p>
diff --git a/docs/4.0/examples/navbar-top-fixed/index.html b/docs/4.0/examples/navbar-top-fixed/index.html
index 18b223fb9..411790ddb 100644
--- a/docs/4.0/examples/navbar-top-fixed/index.html
+++ b/docs/4.0/examples/navbar-top-fixed/index.html
@@ -42,13 +42,13 @@
       </div>
     </nav>
 
-    <div class="container">
+    <main role="main" class="container">
       <div class="jumbotron">
         <h1>Navbar example</h1>
         <p class="lead">This example is a quick exercise to illustrate how fixed to top navbar works. As you scroll, it will remain fixed to the top of your browser's viewport.</p>
         <a class="btn btn-lg btn-primary" href="../../components/navbar/" role="button">View navbar docs &raquo;</a>
       </div>
-    </div>
+    </main>
 
 
     <!-- Bootstrap core JavaScript
diff --git a/docs/4.0/examples/navbar-top/index.html b/docs/4.0/examples/navbar-top/index.html
index e141f3b8c..23db5e5c8 100644
--- a/docs/4.0/examples/navbar-top/index.html
+++ b/docs/4.0/examples/navbar-top/index.html
@@ -42,13 +42,13 @@
       </div>
     </nav>
 
-    <div class="container">
+    <main role="main" class="container">
       <div class="jumbotron">
         <h1>Navbar example</h1>
         <p class="lead">This example is a quick exercise to illustrate how the top-aligned navbar works. As you scroll, this navbar remains in its original position and moves with the rest of the page.</p>
         <a class="btn btn-lg btn-primary" href="../../components/navbar/" role="button">View navbar docs &raquo;</a>
       </div>
-    </div>
+    </main>
 
 
     <!-- Bootstrap core JavaScript
diff --git a/docs/4.0/examples/navbars/index.html b/docs/4.0/examples/navbars/index.html
index bad842040..cebe112f1 100644
--- a/docs/4.0/examples/navbars/index.html
+++ b/docs/4.0/examples/navbars/index.html
@@ -322,16 +322,18 @@
         </div>
       </nav>
 
-      <div class="jumbotron">
-        <div class="col-sm-8 mx-auto">
-          <h1>Navbar examples</h1>
-          <p>This example is a quick exercise to illustrate how the navbar and its contents work. Some navbars extend the width of the viewport, others are confined within a <code>.container</code>. For positioning of navbars, checkout the <a href="../navbar-top/">top</a> and <a href="../navbar-top-fixed/">fixed top</a> examples.</p>
-          <p>At the smallest breakpoint, the collapse plugin is used to hide the links and show a menu button to toggle the collapsed content.</p>
-          <p>
-            <a class="btn btn-primary" href="../../components/navbar/" role="button">View navbar docs &raquo;</a>
-          </p>
+      <main role="main">
+        <div class="jumbotron">
+          <div class="col-sm-8 mx-auto">
+            <h1>Navbar examples</h1>
+            <p>This example is a quick exercise to illustrate how the navbar and its contents work. Some navbars extend the width of the viewport, others are confined within a <code>.container</code>. For positioning of navbars, checkout the <a href="../navbar-top/">top</a> and <a href="../navbar-top-fixed/">fixed top</a> examples.</p>
+            <p>At the smallest breakpoint, the collapse plugin is used to hide the links and show a menu button to toggle the collapsed content.</p>
+            <p>
+              <a class="btn btn-primary" href="../../components/navbar/" role="button">View navbar docs &raquo;</a>
+            </p>
+          </div>
         </div>
-      </div>
+      </main>
     </div>
 
 
diff --git a/docs/4.0/examples/offcanvas/index.html b/docs/4.0/examples/offcanvas/index.html
index 81bebd819..9de9526ec 100644
--- a/docs/4.0/examples/offcanvas/index.html
+++ b/docs/4.0/examples/offcanvas/index.html
@@ -51,7 +51,7 @@
       </div>
     </nav>
 
-    <div class="container">
+    <main role="main" class="container">
 
       <div class="row row-offcanvas row-offcanvas-right">
 
@@ -115,11 +115,11 @@
 
       <hr>
 
-      <footer>
-        <p>&copy; Company 2017</p>
-      </footer>
+    </main><!--/.container-->
 
-    </div><!--/.container-->
+    <footer>
+      <p>&copy; Company 2017</p>
+    </footer>
 
 
     <!-- Bootstrap core JavaScript
diff --git a/docs/4.0/examples/starter-template/index.html b/docs/4.0/examples/starter-template/index.html
index 6d3bef63f..bf37fb1ea 100644
--- a/docs/4.0/examples/starter-template/index.html
+++ b/docs/4.0/examples/starter-template/index.html
@@ -51,14 +51,14 @@
       </div>
     </nav>
 
-    <div class="container">
+    <main role="main" class="container">
 
       <div class="starter-template">
         <h1>Bootstrap starter template</h1>
         <p class="lead">Use this document as a way to quickly start any new project.<br> All you get is this text and a mostly barebones HTML document.</p>
       </div>
 
-    </div><!-- /.container -->
+    </main><!-- /.container -->
 
 
     <!-- Bootstrap core JavaScript
diff --git a/docs/4.0/examples/sticky-footer-navbar/index.html b/docs/4.0/examples/sticky-footer-navbar/index.html
index b4de649a7..70721229a 100644
--- a/docs/4.0/examples/sticky-footer-navbar/index.html
+++ b/docs/4.0/examples/sticky-footer-navbar/index.html
@@ -18,39 +18,41 @@
 
   <body>
 
-    <!-- Fixed navbar -->
-    <nav class="navbar navbar-expand-md navbar-dark fixed-top bg-dark">
-      <a class="navbar-brand" href="#">Fixed navbar</a>
-      <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
-        <span class="navbar-toggler-icon"></span>
-      </button>
-      <div class="collapse navbar-collapse" id="navbarCollapse">
-        <ul class="navbar-nav mr-auto">
-          <li class="nav-item active">
-            <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
-          </li>
-          <li class="nav-item">
-            <a class="nav-link" href="#">Link</a>
-          </li>
-          <li class="nav-item">
-            <a class="nav-link disabled" href="#">Disabled</a>
-          </li>
-        </ul>
-        <form class="form-inline mt-2 mt-md-0">
-          <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
-          <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
-        </form>
-      </div>
-    </nav>
+    <header>
+      <!-- Fixed navbar -->
+      <nav class="navbar navbar-expand-md navbar-dark fixed-top bg-dark">
+        <a class="navbar-brand" href="#">Fixed navbar</a>
+        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
+          <span class="navbar-toggler-icon"></span>
+        </button>
+        <div class="collapse navbar-collapse" id="navbarCollapse">
+          <ul class="navbar-nav mr-auto">
+            <li class="nav-item active">
+              <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
+            </li>
+            <li class="nav-item">
+              <a class="nav-link" href="#">Link</a>
+            </li>
+            <li class="nav-item">
+              <a class="nav-link disabled" href="#">Disabled</a>
+            </li>
+          </ul>
+          <form class="form-inline mt-2 mt-md-0">
+            <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
+            <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
+          </form>
+        </div>
+      </nav>
+    </header>
 
     <!-- Begin page content -->
-    <div class="container">
+    <main role="main" class="container">
       <div class="mt-3">
         <h1>Sticky footer with fixed navbar</h1>
       </div>
       <p class="lead">Pin a fixed-height footer to the bottom of the viewport in desktop browsers with this custom HTML and CSS. A fixed navbar has been added with <code>padding-top: 60px;</code> on the <code>body &gt; .container</code>.</p>
       <p>Back to <a href="../sticky-footer">the default sticky footer</a> minus the navbar.</p>
-    </div>
+    </main>
 
     <footer class="footer">
       <div class="container">
diff --git a/docs/4.0/examples/sticky-footer/index.html b/docs/4.0/examples/sticky-footer/index.html
index 66dcac132..2c24ea62d 100644
--- a/docs/4.0/examples/sticky-footer/index.html
+++ b/docs/4.0/examples/sticky-footer/index.html
@@ -19,13 +19,13 @@
   <body>
 
     <!-- Begin page content -->
-    <div class="container">
+    <main role="main" class="container">
       <div class="mt-1">
         <h1>Sticky footer</h1>
       </div>
       <p class="lead">Pin a fixed-height footer to the bottom of the viewport in desktop browsers with this custom HTML and CSS.</p>
       <p>Use <a href="../sticky-footer-navbar">the sticky footer with a fixed navbar</a> if need be, too.</p>
-    </div>
+    </main>
 
     <footer class="footer">
       <div class="container">
