It’s just not div with the header class your screenshot shows: the complete HTML document below has been inserted into the page, making your markup completely invalid.
This could not have come from WordPress or even your theme… you’ll need to track down how this came about and remove the entire code below (note that I’ve redacted the phone number and email address for your privacy):
<html lang="en">
<head>
<title>Page Title</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
/* Style the body */
body {
font-family: Arial;
margin: 0;
}
/* Header/Logo Title */
.header {
padding: 5px;
text-align: right;
background: #EDFAFE;
color: white;
font-size: 10px;
}
/* Page Content */
.content {padding:10px;}
</style>
</head>
<body>
<div class="header">
<p> 營業時間 禮拜一~禮拜五10am- 4pm 澳洲聯邦認證旅行社 <a href="#" class="fa fa-phone"></a> （+61）1800 xxx xxx <a href="#" class="fa fa-envelope"></a> info@xxxxxxxx.com </p>
</div>
</body>
</html>
