diff --git a/demo/css/main.css b/demo/css/main.css
index a7c674685..f230d2481 100644
--- a/demo/css/main.css
+++ b/demo/css/main.css
@@ -45,6 +45,6 @@
 body {
   background-color: #eff1f4;
 }
-body.bi-theme-dark {
+.bi-theme-dark body {
   background-color: #191B2B;
 }
diff --git a/demo/js/north.js b/demo/js/north.js
index 84b2d2078..d214cdf14 100644
--- a/demo/js/north.js
+++ b/demo/js/north.js
@@ -28,13 +28,13 @@ Demo.North = BI.inherit(BI.Widget, {
                         type: "bi.text_button",
                         text: "星空蓝",
                         handler: function () {
-                            $("body").removeClass("bi-theme-default").addClass("bi-theme-dark");
+                            $("html").removeClass("bi-theme-default").addClass("bi-theme-dark");
                         }
                     }, {
                         type: "bi.text_button",
                         text: "典雅白",
                         handler: function () {
-                            $("body").removeClass("bi-theme-dark").addClass("bi-theme-default");
+                            $("html").removeClass("bi-theme-dark").addClass("bi-theme-default");
                         }
                     }]
                 }
diff --git a/demo/less/main.less b/demo/less/main.less
index afdeded82..662c65ed7 100644
--- a/demo/less/main.less
+++ b/demo/less/main.less
@@ -58,6 +58,6 @@ body {
   background-color: @color-bi-background-normal;
 }
 
-body.bi-theme-dark {
+.bi-theme-dark body {
   background-color: @color-bi-background-normal-theme-dark;
 }
\ No newline at end of file
diff --git a/docs/demo.css b/docs/demo.css
index 2c14653b2..0ce1e8299 100644
--- a/docs/demo.css
+++ b/docs/demo.css
@@ -54,7 +54,7 @@
 body {
   background-color: #eff1f4;
 }
-body.bi-theme-dark {
+.bi-theme-dark body {
   background-color: #191B2B;
 }
 /****添加计算宽度的--运算符直接需要space****/
diff --git a/docs/demo.js b/docs/demo.js
index a185cd476..0faea58a3 100644
--- a/docs/demo.js
+++ b/docs/demo.js
@@ -5585,13 +5585,13 @@ BI.shortcut("demo.main", Demo.Main);Demo.North = BI.inherit(BI.Widget, {
                         type: "bi.text_button",
                         text: "星空蓝",
                         handler: function () {
-                            $("body").removeClass("bi-theme-default").addClass("bi-theme-dark");
+                            $("html").removeClass("bi-theme-default").addClass("bi-theme-dark");
                         }
                     }, {
                         type: "bi.text_button",
                         text: "典雅白",
                         handler: function () {
-                            $("body").removeClass("bi-theme-dark").addClass("bi-theme-default");
+                            $("html").removeClass("bi-theme-dark").addClass("bi-theme-default");
                         }
                     }]
                 }