Add sidebar resizing

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 +475,21 @@ function playpen_text(playpen) {
         }
     });
 
+    sidebarResizeHandle.addEventListener('mousedown', initResize, false);
+
+    function initResize(e) {
+        window.addEventListener('mousemove', resize, false);
+        window.addEventListener('mouseup', stopResize, false);
+    }
+    function resize(e) {
+        document.documentElement.style.setProperty('--sidebar-width', (e.clientX - sidebar.offsetLeft) + 'px');
+    }
+    //on mouseup remove windows functions mousemove & mouseup
+    function stopResize(e) {
+        window.removeEventListener('mousemove', resize, false);
+        window.removeEventListener('mouseup', stopResize, false);
+    }
+
     document.addEventListener('touchstart', function (e) {
         firstContact = {
             x: e.touches[0].clientX,

src/theme/css/chrome.css

@@ -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;
@@ -316,6 +314,27 @@ ul#searchresults span.teaser em {
 .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)));
 }

src/theme/index.hbs

@@ -80,7 +80,10 @@
         </script>
 
         <nav id="sidebar" class="sidebar" aria-label="Table of contents">
+            <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">