Я не понимаю, почему я не вижу свою иконку-конверт, когда HTML-страница отображается в браузере.
Источник ниже:
<!doctype html>
<html>
<head>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/3.3.7/css/font-awesome.min.css" rel="stylesheet" />
<link href='http://fonts.googleapis.com/css?family=Abel|Open+Sans:400,600' rel='stylesheet'>
<style>
body {
padding-top: 20px;
font-size: 16px;
font-family: "Open Sans",serif;
}
h1 {
font-family: "Abel", Arial, sans-serif;
font-weight: 400;
font-size: 40px;
}
.margin-base-vertical {
margin: 40px 0;
}
</style>
</head>
<body>
<div class="container">
<div class="row">
<div class="col-md-6 col-md-offset-3">
<form class="margin-base-vertical">
<p class="input-group">
<span class="input-group-addon"><span class="icon icon-envelope"></span></span>
<input type="text" class="form-control input-lg" name="email" placeholder="webmaster@test.com" />
</p>
<p class="help-block text-center"><small>Subscribe.</small></p>
<p class="text-center">
<button type="submit" class="btn btn-success btn-lg">Submit</button>
</p>
</span>
</form>
</div>
</div>
</div></body>
</html>