Clean up TOC styles and fix bugs

 - Clean up unused TOC styles
 - Fix bug in sticky TOC where if you scrolled down to the bottom to
   make it sticky, then reduce your viewport width to mobile, the TOC
would disappear.
 - Fix empty TOC covering header on a path without any TOC

See
https://gitlab.com/gitlab-com/gitlab-docs/merge_requests/182#note_57833460

4 files changed, 286 insertions, 73 deletions

diff --git a/content/assets/javascripts/classlist-polyfill.js b/content/assets/javascripts/classlist-polyfill.js
new file mode 100644
index 00000000..09b2e8b0
--- /dev/null
+++ b/content/assets/javascripts/classlist-polyfill.js
@@ -0,0 +1,240 @@
+/*
+ * classList.js: Cross-browser full element.classList implementation.
+ * 1.1.20170427
+ *
+ * By Eli Grey, http://eligrey.com
+ * License: Dedicated to the public domain.
+ *   See https://github.com/eligrey/classList.js/blob/master/LICENSE.md
+ */
+
+/*global self, document, DOMException */
+
+/*! @source http://purl.eligrey.com/github/classList.js/blob/master/classList.js */
+
+if ("document" in window.self) {
+
+// Full polyfill for browsers with no classList support
+// Including IE < Edge missing SVGElement.classList
+if (!("classList" in document.createElement("_"))
+	|| document.createElementNS && !("classList" in document.createElementNS("http://www.w3.org/2000/svg","g"))) {
+
+(function (view) {
+
+"use strict";
+
+if (!('Element' in view)) return;
+
+var
+	  classListProp = "classList"
+	, protoProp = "prototype"
+	, elemCtrProto = view.Element[protoProp]
+	, objCtr = Object
+	, strTrim = String[protoProp].trim || function () {
+		return this.replace(/^\s+|\s+$/g, "");
+	}
+	, arrIndexOf = Array[protoProp].indexOf || function (item) {
+		var
+			  i = 0
+			, len = this.length
+		;
+		for (; i < len; i++) {
+			if (i in this && this[i] === item) {
+				return i;
+			}
+		}
+		return -1;
+	}
+	// Vendors: please allow content code to instantiate DOMExceptions
+	, DOMEx = function (type, message) {
+		this.name = type;
+		this.code = DOMException[type];
+		this.message = message;
+	}
+	, checkTokenAndGetIndex = function (classList, token) {
+		if (token === "") {
+			throw new DOMEx(
+				  "SYNTAX_ERR"
+				, "An invalid or illegal string was specified"
+			);
+		}
+		if (/\s/.test(token)) {
+			throw new DOMEx(
+				  "INVALID_CHARACTER_ERR"
+				, "String contains an invalid character"
+			);
+		}
+		return arrIndexOf.call(classList, token);
+	}
+	, ClassList = function (elem) {
+		var
+			  trimmedClasses = strTrim.call(elem.getAttribute("class") || "")
+			, classes = trimmedClasses ? trimmedClasses.split(/\s+/) : []
+			, i = 0
+			, len = classes.length
+		;
+		for (; i < len; i++) {
+			this.push(classes[i]);
+		}
+		this._updateClassName = function () {
+			elem.setAttribute("class", this.toString());
+		};
+	}
+	, classListProto = ClassList[protoProp] = []
+	, classListGetter = function () {
+		return new ClassList(this);
+	}
+;
+// Most DOMException implementations don't allow calling DOMException's toString()
+// on non-DOMExceptions. Error's toString() is sufficient here.
+DOMEx[protoProp] = Error[protoProp];
+classListProto.item = function (i) {
+	return this[i] || null;
+};
+classListProto.contains = function (token) {
+	token += "";
+	return checkTokenAndGetIndex(this, token) !== -1;
+};
+classListProto.add = function () {
+	var
+		  tokens = arguments
+		, i = 0
+		, l = tokens.length
+		, token
+		, updated = false
+	;
+	do {
+		token = tokens[i] + "";
+		if (checkTokenAndGetIndex(this, token) === -1) {
+			this.push(token);
+			updated = true;
+		}
+	}
+	while (++i < l);
+
+	if (updated) {
+		this._updateClassName();
+	}
+};
+classListProto.remove = function () {
+	var
+		  tokens = arguments
+		, i = 0
+		, l = tokens.length
+		, token
+		, updated = false
+		, index
+	;
+	do {
+		token = tokens[i] + "";
+		index = checkTokenAndGetIndex(this, token);
+		while (index !== -1) {
+			this.splice(index, 1);
+			updated = true;
+			index = checkTokenAndGetIndex(this, token);
+		}
+	}
+	while (++i < l);
+
+	if (updated) {
+		this._updateClassName();
+	}
+};
+classListProto.toggle = function (token, force) {
+	token += "";
+
+	var
+		  result = this.contains(token)
+		, method = result ?
+			force !== true && "remove"
+		:
+			force !== false && "add"
+	;
+
+	if (method) {
+		this[method](token);
+	}
+
+	if (force === true || force === false) {
+		return force;
+	} else {
+		return !result;
+	}
+};
+classListProto.toString = function () {
+	return this.join(" ");
+};
+
+if (objCtr.defineProperty) {
+	var classListPropDesc = {
+		  get: classListGetter
+		, enumerable: true
+		, configurable: true
+	};
+	try {
+		objCtr.defineProperty(elemCtrProto, classListProp, classListPropDesc);
+	} catch (ex) { // IE 8 doesn't support enumerable:true
+		// adding undefined to fight this issue https://github.com/eligrey/classList.js/issues/36
+		// modernie IE8-MSW7 machine has IE8 8.0.6001.18702 and is affected
+		if (ex.number === undefined || ex.number === -0x7FF5EC54) {
+			classListPropDesc.enumerable = false;
+			objCtr.defineProperty(elemCtrProto, classListProp, classListPropDesc);
+		}
+	}
+} else if (objCtr[protoProp].__defineGetter__) {
+	elemCtrProto.__defineGetter__(classListProp, classListGetter);
+}
+
+}(window.self));
+
+}
+
+// There is full or partial native classList support, so just check if we need
+// to normalize the add/remove and toggle APIs.
+
+(function () {
+	"use strict";
+
+	var testElement = document.createElement("_");
+
+	testElement.classList.add("c1", "c2");
+
+	// Polyfill for IE 10/11 and Firefox <26, where classList.add and
+	// classList.remove exist but support only one argument at a time.
+	if (!testElement.classList.contains("c2")) {
+		var createMethod = function(method) {
+			var original = DOMTokenList.prototype[method];
+
+			DOMTokenList.prototype[method] = function(token) {
+				var i, len = arguments.length;
+
+				for (i = 0; i < len; i++) {
+					token = arguments[i];
+					original.call(this, token);
+				}
+			};
+		};
+		createMethod('add');
+		createMethod('remove');
+	}
+
+	testElement.classList.toggle("c3", false);
+
+	// Polyfill for IE 10 and Firefox <24, where classList.toggle does not
+	// support the second argument.
+	if (testElement.classList.contains("c3")) {
+		var _toggle = DOMTokenList.prototype.toggle;
+
+		DOMTokenList.prototype.toggle = function(token, force) {
+			if (1 in arguments && !this.contains(token) === !force) {
+				return force;
+			} else {
+				return _toggle.call(this, token);
+			}
+		};
+
+	}
+
+	testElement = null;
+}());
+
+}
diff --git a/content/assets/javascripts/docs.js b/content/assets/javascripts/docs.js
index 4d894590..100a0f9b 100644
--- a/content/assets/javascripts/docs.js
+++ b/content/assets/javascripts/docs.js
@@ -1,3 +1,5 @@
+var NAV_INLINE_BREAKPOINT = 1100;
+
 var navtoggle = document.getElementById("docs-nav-toggle");
 if (navtoggle) {
   navtoggle.addEventListener("click", toggleNavigation);
@@ -43,14 +45,18 @@ function toggleNavigation() {
 
           var sidebarHeight = sidebar.querySelector('ul').getBoundingClientRect().height + 55;
 
+          // When we scroll down to the bottom, we don't want the footer covering
+          // the TOC list (sticky behavior)
           document.addEventListener('scroll', function() {
-            if (window.innerWidth < 1099) return;
+            var isTouchingBottom = false;
+            if (window.innerWidth >= NAV_INLINE_BREAKPOINT) {
+              isTouchingBottom  = window.scrollY + sidebarHeight >= main[0].offsetHeight;
+            }
 
-            if (window.scrollY + sidebarHeight >= main[0].offsetHeight) {
-              sidebar.style.position = 'absolute';
+            sidebar.classList.toggle('doc-nav-bottom-touching', isTouchingBottom)
+            if (isTouchingBottom) {
               sidebar.style.top = (main[0].offsetHeight - sidebarHeight) + 'px';
             } else {
-              sidebar.style.position = '';
               sidebar.style.top = '';
             }
           }, { passive : true });
diff --git a/content/assets/stylesheets/stylesheet.scss b/content/assets/stylesheets/stylesheet.scss
index 30cf3519..cf0e206f 100644
--- a/content/assets/stylesheets/stylesheet.scss
+++ b/content/assets/stylesheets/stylesheet.scss
@@ -258,10 +258,6 @@ h6 {
   .breadcrumbs {
     font-style: italic;
 
-    li {
-      margin-top: 20px;
-    }
-
     .last-updated {
       color: $color-light-gray;
       font-size: 13px;
@@ -270,6 +266,7 @@ h6 {
 }
 
 .header {
+  z-index: 1;
   background: $main-background-color;
   position: relative;
   width: 100%;
diff --git a/content/assets/stylesheets/toc.scss b/content/assets/stylesheets/toc.scss
index 4a1ad2fa..852e3522 100644
--- a/content/assets/stylesheets/toc.scss
+++ b/content/assets/stylesheets/toc.scss
@@ -4,8 +4,22 @@ version: 2
 
 @import "variables";
 
+.clear {
+  clear: both;
+}
+
+.doc-nav {
+  h4 {
+    padding-bottom: 5px;
+  }
+
+  li > a {
+    font-size: 14px;
+  }
+}
+
 // ToC styles
-.breadcrumbs + ul, .doc-nav > ul, .quick-nav ul {
+.doc-nav > ul {
   background: $body-background-color;
   padding: 20px;
   margin-top: 60px;
@@ -20,29 +34,8 @@ version: 2
   }
 }
 
-.doc-nav, .quick-nav {
-  h4 {
-    padding-bottom: 5px;
-  }
-
-  li > a {
-    font-size: 14px;
-  }
-}
-
-.clear {
-  clear: both;
-}
-
 // not wide enough to show quick nav and toc
 @media(max-width:1099px) {
-  .doc-nav {
-    margin: 0 auto;
-    background: $white;
-    width: inherit;
-    max-width: 900px;
-  }
-
   .doc-nav > ul {
     margin: 0;
   }
@@ -53,10 +46,6 @@ version: 2
     margin: 0 auto;
     max-width: 900px;
   }
-
-  .quick-nav {
-    display: none;
-  }
 }
 
 // wide enough to show toc but not quick nav
@@ -78,65 +67,46 @@ version: 2
     right: 0;
     padding-top: 55px;
     overflow-y: scroll;
-    height: 100%;
-  }
-
-  .doc-nav ul ul {
-    padding-left: 25px;
+    height: 100vh;
   }
 
-  .doc-nav > ul .quick-nav ul {
-    margin: 0;
+  .doc-nav-bottom-touching {
+    position: absolute;
   }
 
-  .doc-nav, .quick-nav {
-    width: 25%;
+  .doc-nav ul ul {
+    padding-left: 25px;
   }
 }
 
 @media(min-width:1100px) and (max-width:1600px) {
-  .quick-nav {
-    display: none;
+  .main.class.has-toc {
+    width: 70vw;
+    max-width: 70vw;
+    float: left;
   }
 
   .doc-nav {
-    width: 30%;
-    max-width: 30%;
+    width: 30vw;
+    max-width: 30vw;
   }
-
-  .main.class.has-toc {
-    width: 70%;
-    max-width: 70%;
-    float: left;
+  .doc-nav-bottom-touching {
+    right: -30vw;
   }
 }
 
 // wide enough to show quick nav and toc
 @media(min-width:1601px) {
   .main.class.has-toc {
-    width: 50%;
-    margin-left: 25%;
-    max-width: 50%;
-  }
-
-  .quick-nav {
-    position: fixed;
-    top: 0;
-    padding-top: 55px;
-    left: 0;
-    overflow-y: scroll;
-    height: 100%;
+    width: 50vw;
+    max-width: 50vw;
+    margin-left: 25vw;
   }
 
-  .quick-nav ul ul {
-    padding-bottom: 0;
-  }
-
-  .quick-nav h4 {
-    margin-top: 25px;
+  .doc-nav {
+    width: 25vw;
   }
-
-  .quick-nav h4:first-child {
-    margin-top: 10px;
+  .doc-nav-bottom-touching {
+    right: -25vw;
   }
 }