diff --git a/src/theme/book.js b/src/theme/book.js
index c2b1b0f2..943e0a1b 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -435,6 +435,7 @@ function playpen_text(playpen) {
     var sidebar = document.getElementById("sidebar");
     var sidebarLinks = document.querySelectorAll('#sidebar a');
     var sidebarToggleButton = document.getElementById("sidebar-toggle");
+    var sidebarResizeHandle = document.getElementById("sidebar-resize-handle");
     var firstContact = null;
 
     function showSidebar() {
@@ -474,6 +475,23 @@ function playpen_text(playpen) {
         }
     });
 
+    sidebarResizeHandle.addEventListener('mousedown', initResize, false);
+
+    function initResize(e) {
+        window.addEventListener('mousemove', resize, false);
+        window.addEventListener('mouseup', stopResize, false);
+        html.classList.add('sidebar-resizing');
+    }
+    function resize(e) {
+        document.documentElement.style.setProperty('--sidebar-width', (e.clientX - sidebar.offsetLeft) + 'px');
+    }
+    //on mouseup remove windows functions mousemove & mouseup
+    function stopResize(e) {
+        html.classList.remove('sidebar-resizing');
+        window.removeEventListener('mousemove', resize, false);
+        window.removeEventListener('mouseup', stopResize, false);
+    }
+
     document.addEventListener('touchstart', function (e) {
         firstContact = {
             x: e.touches[0].clientX,
diff --git a/src/theme/css/chrome.css b/src/theme/css/chrome.css
index 7459fc78..db4970b6 100644
--- a/src/theme/css/chrome.css
+++ b/src/theme/css/chrome.css
@@ -78,7 +78,7 @@ html:not(.sidebar-visible) #menu-bar:not(:hover).folded > #menu-bar-sticky-conta
     display: flex;
     margin: 0 5px;
 }
-.no-js .left-buttons { 
+.no-js .left-buttons {
     display: none;
 }
 
@@ -145,7 +145,7 @@ html:not(.sidebar-visible) #menu-bar:not(:hover).folded > #menu-bar-sticky-conta
     display: none;
 }
 
-.mobile-nav-chapters { 
+.mobile-nav-chapters {
     font-size: 2.5em;
     text-align: center;
     text-decoration: none;
@@ -301,8 +301,6 @@ ul#searchresults span.teaser em {
     top: 0;
     bottom: 0;
     width: var(--sidebar-width);
-    overflow-y: auto;
-    padding: 10px 10px;
     font-size: 0.875em;
     box-sizing: border-box;
     -webkit-overflow-scrolling: touch;
@@ -310,12 +308,39 @@ ul#searchresults span.teaser em {
     background-color: var(--sidebar-bg);
     color: var(--sidebar-fg);
 }
-.js .sidebar {
+.sidebar-resizing {
+    -moz-user-select: none;
+    -webkit-user-select: none;
+    -ms-user-select: none;
+    user-select: none;
+}
+.js:not(.sidebar-resizing) .sidebar {
     transition: transform 0.3s; /* Animation: slide away */
 }
 .sidebar code {
     line-height: 2em;
 }
+.sidebar .sidebar-scrollbox {
+    overflow-y: auto;
+    position: absolute;
+    top: 0;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    padding: 10px 10px;
+}
+.sidebar .sidebar-resize-handle {
+    position: absolute;
+    cursor: col-resize;
+    width: 0;
+    right: 0;
+    top: 0;
+    bottom: 0;
+}
+.js .sidebar .sidebar-resize-handle {
+    cursor: col-resize;
+    width: 5px;
+}
 .sidebar-hidden .sidebar {
     transform: translateX(calc(0px - var(--sidebar-width)));
 }
@@ -368,7 +393,7 @@ ul#searchresults span.teaser em {
     background-color: var(--sidebar-spacer);
 }
 
-@media (-moz-touch-enabled: 1), (pointer: coarse) { 
+@media (-moz-touch-enabled: 1), (pointer: coarse) {
     .chapter li a { padding: 5px 0; }
     .spacer { margin: 10px 0; }
 }
diff --git a/src/theme/css/general.css b/src/theme/css/general.css
index aedfb332..f0aefa2a 100644
--- a/src/theme/css/general.css
+++ b/src/theme/css/general.css
@@ -30,7 +30,7 @@ h4, h5 { margin-top: 2em; }
 
 .header + .header h3,
 .header + .header h4,
-.header + .header h5 { 
+.header + .header h5 {
     margin-top: 1em;
 }
 
@@ -51,7 +51,7 @@ a.header:target h4:before {
 .page-wrapper {
     box-sizing: border-box;
 }
-.js .page-wrapper {
+.js:not(.sidebar-resizing) .page-wrapper {
     transition: margin-left 0.3s ease, transform 0.3s ease; /* Animation: slide away */
 }
 
@@ -141,4 +141,3 @@ blockquote {
 .tooltipped .tooltiptext {
     visibility: visible;
 }
-  
\ No newline at end of file
diff --git a/src/theme/index.hbs b/src/theme/index.hbs
index bfe4283a..cce561f6 100644
--- a/src/theme/index.hbs
+++ b/src/theme/index.hbs
@@ -61,7 +61,7 @@
         <!-- Set the theme before any content is loaded, prevents flash -->
         <script type="text/javascript">
             var theme;
-            try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { } 
+            try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
             if (theme === null || theme === undefined) { theme = default_theme; }
             document.body.className = theme;
             document.querySelector('html').className = theme + ' js';
@@ -80,7 +80,10 @@
         </script>
 
         <nav id="sidebar" class="sidebar" aria-label="Table of contents">
-            {{#toc}}{{/toc}}
+            <div class="sidebar-scrollbox">
+                {{#toc}}{{/toc}}
+            </div>
+            <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
         </nav>
 
         <div id="page-wrapper" class="page-wrapper">
@@ -110,7 +113,7 @@
                             {{/if}}
                         </div>
 
-                        <h1 class="menu-title">{{ book_title }}</h1> 
+                        <h1 class="menu-title">{{ book_title }}</h1>
 
                         <div class="right-buttons">
                             <a href="{{ path_to_root }}print.html" title="Print this book" aria-label="Print this book">