diff --git a/assets/css/devportal.css b/assets/css/devportal2020.css
similarity index 100%
rename from assets/css/devportal.css
rename to assets/css/devportal2020.css
diff --git a/assets/css/devportal.css.map b/assets/css/devportal2020.css.map
similarity index 100%
rename from assets/css/devportal.css.map
rename to assets/css/devportal2020.css.map
diff --git a/tool/template-base.html b/tool/template-base.html
index fa5cf5806d..9a159d4c2f 100644
--- a/tool/template-base.html
+++ b/tool/template-base.html
@@ -32,7 +32,7 @@
     {% if target.lang=="ja" %}
     <link href="{{currentpage.prefix}}assets/css/fonts-ja.css" rel="stylesheet" />
     {% endif %}
-    <link href="{{currentpage.prefix}}assets/css/devportal.css" rel="stylesheet" />
+    <link href="{{currentpage.prefix}}assets/css/devportal2020.css" rel="stylesheet" />
 
     <!-- Google Analytics -->
     <script async src="https://www.googletagmanager.com/gtag/js?id=UA-45576805-2"></script>