diff --git a/docs/index.html b/docs/index.html
index a0d670e71..3f44faa33 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -158,7 +158,7 @@
                 <a href="https://github.com/krahets/hello-algo/releases">
                     <img class="device-on-hover" style="height: 75%;" src="assets/hero/pdf_ipad.png" alt="">
                     <div class="text-button">
-                        <span>下载 PDF</span>
+                        <span>下载 PDF/EPUB</span>
                         <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512">
                             <path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z" />
                         </svg>
diff --git a/en/docs/index.html b/en/docs/index.html
index 181fa0d27..0e7e348e2 100644
--- a/en/docs/index.html
+++ b/en/docs/index.html
@@ -158,7 +158,7 @@
                 <a href="https://github.com/krahets/hello-algo/releases">
                     <img class="device-on-hover" style="height: 75%;" src="../assets/hero/pdf_ipad.png" alt="">
                     <div class="text-button">
-                        <span>PDF</span>
+                        <span>PDF/EPUB</span>
                         <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512">
                             <path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z" />
                         </svg>
diff --git a/ja/docs/index.html b/ja/docs/index.html
index 55a323020..66f476de9 100644
--- a/ja/docs/index.html
+++ b/ja/docs/index.html
@@ -158,7 +158,7 @@
                 <a href="https://github.com/krahets/hello-algo/releases">
                     <img class="device-on-hover" style="height: 75%;" src="../assets/hero/pdf_ipad.png" alt="">
                     <div class="text-button">
-                        <span>PDF をダウンロード</span>
+                        <span>PDF/EPUB をダウンロード</span>
                         <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512">
                             <path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z" />
                         </svg>
diff --git a/zh-hant/docs/index.html b/zh-hant/docs/index.html
index f5dd8edfc..65ec1ab16 100644
--- a/zh-hant/docs/index.html
+++ b/zh-hant/docs/index.html
@@ -158,7 +158,7 @@
                 <a href="https://github.com/krahets/hello-algo/releases">
                     <img class="device-on-hover" style="height: 75%;" src="../assets/hero/pdf_ipad.png" alt="">
                     <div class="text-button">
-                        <span>下載 PDF</span>
+                        <span>下載 PDF/EPUB</span>
                         <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512">
                             <path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z" />
                         </svg>