diff --git a/assets/gitbook-fix.css b/assets/gitbook-fix.css
new file mode 100644
index 0000000..2fbfbf1
--- /dev/null
+++ b/assets/gitbook-fix.css
@@ -0,0 +1,29 @@
+
+.fold > ul {
+	max-height: 0;
+	overflow: hidden;
+	transition-duration: 0.5s;
+}
+
+.fold.on > ul {
+	max-height: unset;
+}
+
+.book .book-summary ul.summary li a, .book .book-summary ul.summary li span {
+	padding-left: 30px;
+	cursor: pointer;
+}
+
+.book .book-summary .exc-trigger {
+	position: absolute;
+	left: 12px;
+	top: 12px;
+}
+
+.book .book-summary .on > a .exc-trigger:before {
+	content: "\f078";
+}
+
+.book .book-summary .exc-trigger:before {
+	content: "\f054";
+}
diff --git a/assets/gitbook-fix.js b/assets/gitbook-fix.js
index b64674b..860e492 100644
--- a/assets/gitbook-fix.js
+++ b/assets/gitbook-fix.js
@@ -21,3 +21,11 @@ window.onload = function () {
 	}
 	
 };
+
+for (let node of document.getElementsByClassName("fold")) {
+	node.childNodes[0].addEventListener("click", function () {
+		if (node.classList.contains("on")) {
+			node.classList.remove("on");
+		} else node.classList.add("on");
+	});
+}
diff --git a/src/Data/SiteMeta.php b/src/Data/SiteMeta.php
index ca01ecb..8e498be 100644
--- a/src/Data/SiteMeta.php
+++ b/src/Data/SiteMeta.php
@@ -24,6 +24,7 @@ class SiteMeta {
 	public static function getGitbookStylesheetsList (): array {
 		return array(
 			"/assets/gitbook/style.css",
+			"/assets/gitbook-fix.css",
 		);
 	}
 	
diff --git a/src/Element/BookCollection.php b/src/Element/BookCollection.php
index 7c3a2be..774487e 100644
--- a/src/Element/BookCollection.php
+++ b/src/Element/BookCollection.php
@@ -72,7 +72,7 @@ class BookCollection {
 	
 	public function getHtml (): string {
 		$str = "";
-		if ($this->name != self::ROOT) $str .= "<li><a class='book-collection' href='#'>$this->name</a><ul class='book-collection summary'>";
+		if ($this->name != self::ROOT) $str .= "<li class='book-collection fold'><a class='book-collection' href='#'>$this->name<i class='exc-trigger fa'></i></a><ul class='book-collection summary'>";
 		foreach ($this->array as $node) {
 			$str .= $node->getHtml();
 		}
diff --git a/src/Element/BookContent/Chapter.php b/src/Element/BookContent/Chapter.php
index b5ffb9a..5eed99b 100644
--- a/src/Element/BookContent/Chapter.php
+++ b/src/Element/BookContent/Chapter.php
@@ -66,7 +66,7 @@ class Chapter {
 	
 	public function getSummaryHtml (): string {
 		$str = "";
-		if ($this->parent != null) $str .= "<li class='chapter'><a class='page-chapter' href='#'>$this->name</a><ul class='page-chapter summary'>";
+		if ($this->parent != null) $str .= "<li class='chapter fold'><a class='page-chapter' href='#'>$this->name<i class='exc-trigger fa'></i></a><ul class='page-chapter summary'>";
 		foreach ($this->childs as $node) {
 			$str .= $node->getSummaryHtml();
 		}
diff --git a/src/Element/LinkCollection.php b/src/Element/LinkCollection.php
index 560fb69..eb170fc 100644
--- a/src/Element/LinkCollection.php
+++ b/src/Element/LinkCollection.php
@@ -72,7 +72,7 @@ class LinkCollection {
 	
 	public function getHtml (): string {
 		$str = "";
-		if ($this->name != self::ROOT) $str .= "<li><a class='link-collection chapter' href='#'>$this->name</a><ul class='link-collection articles'>";
+		if ($this->name != self::ROOT) $str .= "<li class='link-collection fold'><a class='link-collection chapter' href='#'>$this->name<i class='exc-trigger fa'></i></a><ul class='link-collection articles'>";
 		foreach ($this->array as $node) {
 			$str .= $node->getHtml();
 		}