diff --git a/lib/server/generate.js b/lib/server/generate.js
index 22e5a0563d..f91ac75ae3 100644
--- a/lib/server/generate.js
+++ b/lib/server/generate.js
@@ -56,6 +56,18 @@ function execute() {
     return rawContent.replace(TABLE_OF_CONTENTS_TOKEN, tableOfContents);
   };
 
+  function isSeparateCss(file) {
+    if (!siteConfig.separateCss) {
+      return false;
+    }
+    for (let i = 0; i < siteConfig.separateCss.length; i++) {
+      if (file.includes(siteConfig.separateCss[i])) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   console.log("generate.js triggered...");
 
   const regexSubFolder = /docs\/(.*)\/.*/;
@@ -255,10 +267,7 @@ function execute() {
   /* copy all static files from user */
   files = glob.sync(CWD + "/static/**");
   files.forEach(file => {
-    if (
-      file.match(/\.css$/) &&
-      siteConfig.separateCss.indexOf(path.basename(file)) == -1
-    ) {
+    if (file.match(/\.css$/) && !isSeparateCss(file)) {
       const mainCss =
         __dirname +
         "/../../build" +
diff --git a/lib/server/server.js b/lib/server/server.js
index 97f6db8981..510e8cbc3d 100644
--- a/lib/server/server.js
+++ b/lib/server/server.js
@@ -111,6 +111,20 @@ function execute(port) {
 
   /****************************************************************************/
 
+  function isSeparateCss(file) {
+    if (!siteConfig.separateCss) {
+      return false;
+    }
+    for (let i = 0; i < siteConfig.separateCss.length; i++) {
+      if (file.includes(siteConfig.separateCss[i])) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /****************************************************************************/
+
   console.log("server.js triggered...");
 
   reloadMetadataCategories();
@@ -354,7 +368,7 @@ function execute(port) {
     let files = glob.sync(CWD + "/static/**/*.css");
 
     files.forEach(file => {
-      if (siteConfig.separateCss.indexOf(path.basename(file)) != -1) {
+      if (isSeparateCss(file)) {
         return;
       }
       cssContent =
diff --git a/package.json b/package.json
index 44e6b248bc..347561b5d7 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
     "shelljs": "^0.7.8"
   },
   "name": "docusaurus",
-  "version": "1.0.0-alpha.25",
+  "version": "1.0.0-alpha.26",
   "bin": {
     "docusaurus-start": "./lib/start-server.js",
     "docusaurus-build": "./lib/build-files.js",