diff --git a/about.html b/about.html
index 53f8ada..da0348a 100644
--- a/about.html
+++ b/about.html
@@ -59,7 +59,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 </header>
 
 
-<div id="page-content">
+<main>
 	
 	<div id="sidebar" class="sticky">
 		<h1>About</h1>
@@ -116,7 +116,7 @@ <h1>Related Projects</h1>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 	
diff --git a/assets/css/style-gsod.css b/assets/css/style-gsod.css
index c75191d..f5dfa5c 100644
--- a/assets/css/style-gsod.css
+++ b/assets/css/style-gsod.css
@@ -13,7 +13,7 @@ body {
 
 #page-wrap {width:1000px; margin:0px auto; border:1px solid #fff; padding:20px;}
 
-#page-content {
+main {
 	background:#fff;
 	position:relative;
 	padding: 20px 20px 20px 20px;
diff --git a/assets/css/style.css b/assets/css/style.css
index cd54255..c0c151f 100644
--- a/assets/css/style.css
+++ b/assets/css/style.css
@@ -153,11 +153,12 @@ border: none !important;
 opacity:0.8;
 }
 
-#page-content {
-	background:light-dark(#ffffe5,#141400); /* #FFFFE5 BACKGROUND_COLOR - pale yellow/cream from colormap.cc */
-	position:relative; padding:20px 20px 0px 20px;
-	box-shadow: 1px 1px 12px 2px light-dark(#aaa, #222);
-	border-radius:0px 0px 12px 12px;
+main {
+    background: light-dark(#ffffe5, #141400); /* #FFFFE5 BACKGROUND_COLOR - pale yellow/cream from colormap.cc */
+    border-radius: 0px 0px 12px 12px;
+    box-shadow: 1px 1px 12px 2px light-dark(#aaa, #222);
+    padding: 20px 20px 0px 20px;
+    position: relative;
 }
 
 #sidebar{width:220px; padding:10px; float:left; background:light-dark(#fff, #1b1b1b); border-radius:8px; border:1px solid light-dark(#ddd, #444); margin-bottom:20px;}
diff --git a/community.html b/community.html
index aa88de9..d945efb 100644
--- a/community.html
+++ b/community.html
@@ -59,7 +59,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar" class="sticky">
 		<h1>Community</h1>
@@ -174,7 +174,7 @@ <h1>Other</h1>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/documentation-articles.html b/documentation-articles.html
index f7cfaf4..5a24088 100644
--- a/documentation-articles.html
+++ b/documentation-articles.html
@@ -58,7 +58,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar" class="sticky">
 		<h1><a href="documentation.html">Documentation</a></h1>
@@ -236,7 +236,7 @@ <h3>Jan 2010</h3>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/documentation-books.html b/documentation-books.html
index 26a292e..501ac14 100644
--- a/documentation-books.html
+++ b/documentation-books.html
@@ -60,7 +60,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar" class="sticky">
 		<h1><a href="documentation.html">Documentation</a></h1>
@@ -953,7 +953,7 @@ <h2 class="link-hover">Un reloj de Sol digital<span> <a class="section-link" hre
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/documentation-videos.html b/documentation-videos.html
index 1812e49..a3640f5 100644
--- a/documentation-videos.html
+++ b/documentation-videos.html
@@ -58,7 +58,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar" class="sticky">
 		<h1><a href="documentation.html">Documentation</a></h1>
@@ -142,7 +142,7 @@ <h2 id="introduction"><a href="https://www.youtube.com/watch?v=dzzFOU_Ggrs">Open
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/documentation.html b/documentation.html
index f5b2cb0..b3879bb 100644
--- a/documentation.html
+++ b/documentation.html
@@ -58,7 +58,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 	
 	<div id="sidebar" class="sticky">
 		<h1><a href="documentation.html">Documentation</a></h1>
@@ -201,7 +201,7 @@ <h1><a href="cheatsheet/index.html" target="_blank">Cheat Sheet</a></h1>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 	
diff --git a/downloads.html b/downloads.html
index 9076fb7..04d713e 100644
--- a/downloads.html
+++ b/downloads.html
@@ -90,7 +90,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar" class="sticky">
 		<h1>Downloads</h1>
@@ -755,7 +755,7 @@ <h1>Signature</h1>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/gallery.html b/gallery.html
index 7b66aa9..055f66e 100644
--- a/gallery.html
+++ b/gallery.html
@@ -64,7 +64,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar" class="sticky">
 		<h1>Gallery</h1>
@@ -95,7 +95,7 @@ <h1>OpenSCAD Gallery</h1>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/gsod-2019.html b/gsod-2019.html
index 759e010..c0f2e8d 100644
--- a/gsod-2019.html
+++ b/gsod-2019.html
@@ -13,7 +13,7 @@
 
 <div id="page-wrap">
 
-<div id="page-content">
+<main>
 
 <h1><span class="green">Open</span><span class="yellow">SCAD</span> - Google Season of Docs 2019</h1>
 
@@ -206,7 +206,7 @@ <h2>Contact</h2>
 
 <small>Portions of this page are reproduced from work created and <a href="https://developers.google.com/readme/policies/">shared by Google</a> and used according to terms described in the <a href="http://creativecommons.org/licenses/by/3.0/">Creative Commons 3.0 Attribution License</a> | Logo - source: <a href="https://developers.google.com/season-of-docs/docs/press">https://developers.google.com/season-of-docs/docs/press</a> | Citation in Paragraph "About Google Season of Docs" - source: <a href="https://developers.google.com/season-of-docs/docs/">https://developers.google.com/season-of-docs/docs/</a></small>
 
-</div><!--#page-content end-->
 </div><!--#page-wrap end-->
+</main>
 </body>
 </html>
diff --git a/gsod-2020.html b/gsod-2020.html
index 21bae70..30d547e 100644
--- a/gsod-2020.html
+++ b/gsod-2020.html
@@ -13,7 +13,7 @@
 
 <div id="page-wrap">
 
-<div id="page-content">
+<main>
 
 <h1><span class="green">Open</span><span class="yellow">SCAD</span> - Google Season of Docs 2020</h1>
 
@@ -417,7 +417,7 @@ <h2>Contact</h2>
     | Citation in Paragraph "About Google Season of Docs" - source: <a href="https://developers.google.com/season-of-docs/docs/">https://developers.google.com/season-of-docs/docs/</a>
 </small>
 
-</div><!--#page-content end-->
 </div><!--#page-wrap end-->
+</main>
 </body>
 </html>
diff --git a/howto/MakeCodeParametric.html b/howto/MakeCodeParametric.html
index e0f0bab..7b8ef97 100644
--- a/howto/MakeCodeParametric.html
+++ b/howto/MakeCodeParametric.html
@@ -17,7 +17,7 @@
 
     <div id="page-wrap">
 
-        <div id="page-content">
+        <main>
 
             <h1><span class="green">Open</span><span class="yellow">SCAD</span> - HowTo</h1>
 
@@ -211,7 +211,7 @@ <h1><span class="green">Open</span><span class="yellow">SCAD</span> - HowTo</h1>
             <p>All the general-purpose functions/modules should be stowed away in another file and `use &lt;...&gt;`
                 them over and over across files that represent logical parts.</p>
 
-        </div>
+        </main>
 
     </div>
 
diff --git a/index.html b/index.html
index e95f390..ac4a432 100644
--- a/index.html
+++ b/index.html
@@ -100,7 +100,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar">
     <div style="padding-bottom: 0.5rem;">
@@ -183,7 +183,7 @@ <h1><a href="cheatsheet/index.html" target="_blank">Cheat Sheet</a></h1>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/libraries.html b/libraries.html
index 5081d6a..898ccfb 100644
--- a/libraries.html
+++ b/libraries.html
@@ -58,7 +58,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
   </div>
 </header>
 
-<div id="page-content">
+<main>
 
   <div id="sidebar" class="sticky">
     <h1>Libraries</h1>
@@ -456,7 +456,7 @@ <h2 id="lego">Technic.scad</h2>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/lists.html b/lists.html
index 4ad157e..ae793a9 100644
--- a/lists.html
+++ b/lists.html
@@ -58,7 +58,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar" class="sticky">
 		<h1><a href="documentation.html">Documentation</a></h1>
@@ -99,7 +99,7 @@ <h1><a href="documentation.html">Documentation</a></h1>
 <script src="https://files.openscad.org/lists/news.jsonp"></script>
 <script src="https://files.openscad.org/lists/gallery.jsonp"></script>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>
 
diff --git a/news.html b/news.html
index 5b0b265..93c1110 100644
--- a/news.html
+++ b/news.html
@@ -59,7 +59,7 @@ <h2 class="subtitle" style="position:relative; left:45px;">The Programmers Solid
 	</div>
 </header>
 
-<div id="page-content">
+<main>
 
 	<div id="sidebar" class="sticky">
 		<h1>News</h1>
@@ -1123,7 +1123,7 @@ <h3>Features</h3>
 
 <div class="clear"></div>
 
-</div><!--#page-content end-->
+</main>
 
 <footer>