mainpage.html

<!DOCTYPE html>
<html lang="de">
  <head>
  <meta charset="UTF-8"/>
  <title>Nuclear Football</title>
  <style>


form {
	width: 50em;
	border: 1px solid;
	padding-top: .5em;
}


fieldset {
  border: 1px solid #e7c157;
}

input {
	padding: .5em;
	background-color: #fffbf0;
	border: 1px solid #e7c157;
	width: 10em;
}
select {
	padding: .3em;
	background-color: #fffbf0;
	border: 1px solid #e7c157;
	width: 30em;
}

label {
	display: inline-block;
	width: 12em;
	margin-bottom: 1em;
	line-height: 2em;
	text-align: right;
}

label::after {
	content: ": ";
}

input:invalid {
	border: 1px solid red;
}

button {
	margin-left: 1em;
	width: 10em;
	margin-top: 1em;
	margin-bottom: 1em;
}
</style>
 </head>
 <body>
<h1>Karten-Zuweisung</h1>
	<main>
		<form method="POST">
      #NEW_CARD_SELECT#
      <button type="submit" formaction="/saveassignment">absenden</button>
		</form>
	</main> 
</body>
</html>