diff --git a/server/src/main/resources/web/compress.ftl b/server/src/main/resources/web/compress.ftl
index b57018eb..d40aef7c 100644
--- a/server/src/main/resources/web/compress.ftl
+++ b/server/src/main/resources/web/compress.ftl
@@ -779,6 +779,10 @@
         toggleTreePanelIconEl.textContent = collapsed ? ">" : "<";
     }
 
+    function isDirectoryNode(node) {
+        return !!node && Array.isArray(node.children);
+    }
+
     function countTreeStats(nodes) {
         var stats = { folders: 0, files: 0 };
         var queue = [].concat(nodes || []);
@@ -787,7 +791,7 @@
             if (!node) {
                 continue;
             }
-            if (node.children && node.children.length) {
+            if (isDirectoryNode(node)) {
                 stats.folders += 1;
                 queue = queue.concat(node.children);
             } else {
@@ -841,7 +845,8 @@
 
     function normalizeTreeNodes(nodes) {
         (nodes || []).forEach(function (node) {
-            if (node.children && node.children.length) {
+            if (isDirectoryNode(node)) {
+                node.isParent = true;
                 normalizeTreeNodes(node.children);
                 return;
             }
@@ -851,7 +856,7 @@
     }
 
     function decorateTreeNode(treeId, treeNode) {
-        if (treeNode.isParent) {
+        if (isDirectoryNode(treeNode)) {
             return;
         }
         var anchor = $("#" + treeNode.tId + "_a");
@@ -903,7 +908,7 @@
     }
 
     function handleNodeClick(event, treeId, treeNode) {
-        if (treeNode.isParent) {
+        if (isDirectoryNode(treeNode)) {
             zTreeObj.expandNode(treeNode, !treeNode.open, false, false, false);
             return false;
         }
diff --git a/server/src/main/resources/web/picture.ftl b/server/src/main/resources/web/picture.ftl
index 4017b5a6..648430a3 100644
--- a/server/src/main/resources/web/picture.ftl
+++ b/server/src/main/resources/web/picture.ftl
@@ -11,10 +11,14 @@
         body {
             background-color: #f1f3f5;
         }
-        .viewer-container:focus,
-        .viewer-container:focus-visible {
+        .viewer-container:focus {
             outline: none !important;
         }
+        .viewer-container:focus-visible {
+            outline: 2px solid rgba(95, 107, 122, 0.65) !important;
+            outline-offset: 2px;
+            box-shadow: 0 0 0 4px rgba(95, 107, 122, 0.14);
+        }
         #image { width: 800px; margin: 0 auto; font-size: 0;}
         #image li {  display: inline-block;width: 50px;height: 50px; margin-left: 1%; padding-top: 1%;}
         /*#dowebok li img { width: 200%;}*/
diff --git a/server/src/test/java/cn/keking/PdfViewerCompatibilityTests.java b/server/src/test/java/cn/keking/PdfViewerCompatibilityTests.java
index 6b04b0f5..dc1a07fb 100644
--- a/server/src/test/java/cn/keking/PdfViewerCompatibilityTests.java
+++ b/server/src/test/java/cn/keking/PdfViewerCompatibilityTests.java
@@ -28,14 +28,14 @@ public class PdfViewerCompatibilityTests {
 
     @Test
     void shouldOpenPdfPreviewWithThumbnailSidebarByDefault() throws IOException {
-        String pdfTemplate = readWebResource("/web/pdf.ftl");
+        String pdfTemplate = readResource("/web/pdf.ftl");
 
         assertTrue(pdfTemplate.contains("#page=1&pagemode=thumbs"));
     }
 
     @Test
     void shouldPreferPdfForOfficePreviewByDefault() throws IOException {
-        String properties = readConfigResource("/application.properties");
+        String properties = readResource("/application.properties");
 
         assertTrue(properties.contains("office.preview.type = ${KK_OFFICE_PREVIEW_TYPE:pdf}"));
     }
@@ -46,18 +46,4 @@ public class PdfViewerCompatibilityTests {
             return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8);
         }
     }
-
-    private String readWebResource(String resourcePath) throws IOException {
-        try (InputStream inputStream = getClass().getResourceAsStream(resourcePath)) {
-            assertNotNull(inputStream);
-            return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8);
-        }
-    }
-
-    private String readConfigResource(String resourcePath) throws IOException {
-        try (InputStream inputStream = getClass().getResourceAsStream(resourcePath)) {
-            assertNotNull(inputStream);
-            return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8);
-        }
-    }
 }