修正

frontend/journal.html

@@ -40,7 +40,22 @@
     <br /><br />
 
     <button onclick="submitJournal()">保存</button>
-    <a href="index.html">← 戻る</a>
+    <button
+      onclick="location.href = 'index.html'"
+      class="back-button"
+      style="
+        margin: 0 0 20px 0;
+        padding: 8px 16px;
+        background: #007bff;
+        color: white;
+        border: none;
+        border-radius: 4px;
+        cursor: pointer;
+        font-size: 14px;
+      "
+    >
+      ← 首ページに戻る
+    </button>
 
     <script src="js/api.js"></script>
     <script src="js/journal.js"></script>