[EDIT]スマホ画面のデザインに統一しました

src/main/resources/templates/footer.html

@@ -4,10 +4,11 @@
 <meta charset="UTF-8" name="viewport" content="width=device-width, initial-scale=1">
 <title>フッター</title>
 <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
+<link rel="stylesheet" th:href="@{/css/style.css}">
 </head>
 <body>
 	
-	<footer th:fragment="footer" class="fixed-bottom border-top py-2" style="background-color:#E3F2FD;">
+	<footer th:fragment="footer" class="fixed-bottom border-top py-2 app-footer" style="background-color:#E3F2FD;">
 		
 	  <nav data-bs-theme="light">
 		<div class="card-footer text-center">