diff --git a/demo.html b/demo.html
index 8d1dd21..bddbf3a 100644
--- a/demo.html
+++ b/demo.html
@@ -143,6 +143,7 @@ function consoleLog(str) {
           var newDiv = document.createElement('div')
           var hr = document.createElement('hr')
           newDiv.innerHTML = html
+          // 激活github-markdown-css
           newDiv.className = 'markdown-body'
           textarea.parentNode.insertBefore(newDiv, textarea.nextSibling)