修正

frontend/opening_balance.html

@@ -40,7 +40,22 @@
     <br />
 
     <button onclick="saveOpeningBalances()">保存</button>
-    <button onclick="location.href = 'trial-balance.html'">← 戻る</button>
+    <button
+      onclick="location.href = 'trial-balance.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;
+      "
+    >
+      ← 試算表に戻る
+    </button>
 
     <script src="js/api.js"></script>
     <script src="js/opening_balance.js"></script>