[EDIT] headerとの間隔を調整しました。

src/main/resources/templates/transaction_create.html

@@ -9,7 +9,7 @@
 	<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
 </head>
 
-<body>
+<body class="pb-5 pt-5">
 
 	<div th:replace="~{header :: header}"></div>
 

src/main/resources/templates/transaction_detail.html

@@ -9,7 +9,7 @@
 	<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
 </head>
 
-<body>
+<body class="pb-5 pt-5">
 
 	<div th:replace="~{header :: header}"></div>
 	<h1 th:text="${today}"></h1>

src/main/resources/templates/transaction_list.html

@@ -9,7 +9,7 @@
 	<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
 </head>
 
-<body>
+<body class="pb-5 pt-5">
 
 	<div th:replace="~{header :: header}"></div>
 	

src/main/resources/templates/transaction_update.html

@@ -9,7 +9,7 @@
 	<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
 </head>
 
-<body>
+<body class="pb-5 pt-5">
 
 	<div th:replace="~{header :: header}"></div>