diff --git a/header.html b/header.html
index 7385463..1412746 100644
--- a/header.html
+++ b/header.html
@@ -1,5 +1,5 @@
<!DOCTYPE html>
-<html>
+<html lang="zh-TW">
<head>
<meta charset="UTF-8">
<title>Markdown 語法說明</title>
diff --git a/index.html b/index.html
index 30d3f3a..3a21300 100644
--- a/index.html
+++ b/index.html
@@ -1,5 +1,5 @@
<!DOCTYPE html>
-<html>
+<html lang="zh-TW">
<head>
<meta charset="UTF-8">
<title>Markdown 語法說明</title>