diff --git a/src/components/ShowFile/ShowFile.vue b/src/components/ShowFile/ShowFile.vue
index 0e4041b..229019f 100644
--- a/src/components/ShowFile/ShowFile.vue
+++ b/src/components/ShowFile/ShowFile.vue
@@ -4358,13 +4358,16 @@ export default {
       return this.notPreviewDialogVisible;
     },
     hasIframePreview(suffix, fileHandlers) {
+      // 将 suffix 转换为小写
+      const lowerCaseSuffix = suffix.toLowerCase();
       for (let key in fileHandlers) {
-        const extensions = key.split(',')
-        if (extensions.includes(suffix)) {
-          return fileHandlers[key]
+        // 将 key 中的扩展名全部转换为小写
+        const extensions = key.split(',').map(extension => extension.toLowerCase());
+        if (extensions.includes(lowerCaseSuffix)) {
+          return fileHandlers[key];
         }
       }
-      return null
+      return null;
     },
     determineDownload(file) {
       this.download(file)
diff --git a/src/components/preview/IframeContentPreview.vue b/src/components/preview/IframeContentPreview.vue
index 65c8795..c927198 100644
--- a/src/components/preview/IframeContentPreview.vue
+++ b/src/components/preview/IframeContentPreview.vue
@@ -13,7 +13,7 @@
               :value="item.value">
             </el-option>
           </el-select>
-          <el-button size="medium" type="primary" @click="openUrl"><svg-icon icon-class="wailian"/></el-button>
+          <el-button title="外部打开" size="medium" type="primary" @click="openUrl"><svg-icon icon-class="wailian"/></el-button>
         </div>
       </div>
     </div>
@@ -153,6 +153,7 @@ export default {
   -webkit-box-pack: center;
   -ms-flex-pack: center;
   justify-content: center;
+  background: #dcdfe6;
   iframe {
     width: 100%;
     height: 100%;