我使用了以前版本的 Bootstrap 并且对此没有任何问题，但是我正在尝试使用 3.0 并且我的类只是彼此重叠，而不是从 keft 浮动到正确，我做错了什么？
我按照本教程http://www.w3resource.com/twitter-bootstrap/grid-system-tutorial.php甚至复制它，因为它让我发疯，但它甚至没有工作。
这是我当前的 HTML
<!DOCTYPE html>
<html>
<head>
<title>Twitter</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<!-- Bootstrap -->
<link href="./css/bootstrap.min.css" rel="stylesheet" media="screen">
<link href="./css/global.css" rel="stylesheet" media="screen">
<!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
<!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
<!--[if lt IE 9]>
<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
<script src="https://oss.maxcdn.com/libs/respond.js/1.3.0/respond.min.js"></script>
<![endif]-->
</head>
<body>
<div class="container">
<div class="row">
<nav class="navbar" role="navigation">
<div class="navbar-header">
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#emproium-navbar-collapse">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#">Branding</a>
</div>
<div class="collapse navbar-collapse" id="emproium-navbar-collapse">
<ul class="nav navbar-nav">
<li><a href="#">Core Collection</a></li>
<li><a href="#">Antiques</a></li>
<li><a href="#">Art</a></li>
<li><a href="#">Furniture</a></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">Home Decor <b class="caret"></b></a>
<ul class="dropdown-menu">
<li><a href="#">Rugs</a></li>
<li><a href="#">Throws</a></li>
<li><a href="#">Quilts</a></li>
<li><a href="#">Accent Pillows</a></li>
<li class="divider"></li>
<li class="dropdown-header">Nav header</li>
<li><a href="#">Separated link</a></li>
<li><a href="#">One more separated link</a></li>
</ul>
</li>
<li><a href="#">Cart</a></li>
<li><a href="#">Contact</a></li>
</ul>
</div><!-- /.navbar-collapse -->
</nav>
<div class="banner span12">
</div>
<div class="tile span4"><p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nam cursus. Morbi ut mi. Nullam enim leo, egestas id, condimentum at, laoreet mattis, massa. Sed eleifend nonummy diam. Praesent mauris ante, elementum et, bibendum at, posuere sit amet, nibh. Duis tincidunt lectus quis dui viverra vestibulum. Suspendisse vulputate aliquam dui. Nulla elementum dui ut augue. Aliquam vehicula mi at mauris. Maecenas placerat, nisl at consequat rhoncus, sem nunc gravida justo, quis eleifend arcu velit quis lacus. Morbi magna magna, tincidunt a, mattis non, imperdiet vitae, tellus. Sed odio est, auctor ac, sollicitudin in, consequat vitae, orci. Fusce id felis. Vivamus sollicitudin metus eget eros.</p></div>
<div class="tile span4"><p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nam cursus. Morbi ut mi. Nullam enim leo, egestas id, condimentum at, laoreet mattis, massa. Sed eleifend nonummy diam. Praesent mauris ante, elementum et, bibendum at, posuere sit amet, nibh. Duis tincidunt lectus quis dui viverra vestibulum. Suspendisse vulputate aliquam dui. Nulla elementum dui ut augue. Aliquam vehicula mi at mauris. Maecenas placerat, nisl at consequat rhoncus, sem nunc gravida justo, quis eleifend arcu velit quis lacus. Morbi magna magna, tincidunt a, mattis non, imperdiet vitae, tellus. Sed odio est, auctor ac, sollicitudin in, consequat vitae, orci. Fusce id felis. Vivamus sollicitudin metus eget eros.</p></div>
<div class="tile span4"><p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nam cursus. Morbi ut mi. Nullam enim leo, egestas id, condimentum at, laoreet mattis, massa. Sed eleifend nonummy diam. Praesent mauris ante, elementum et, bibendum at, posuere sit amet, nibh. Duis tincidunt lectus quis dui viverra vestibulum. Suspendisse vulputate aliquam dui. Nulla elementum dui ut augue. Aliquam vehicula mi at mauris. Maecenas placerat, nisl at consequat rhoncus, sem nunc gravida justo, quis eleifend arcu velit quis lacus. Morbi magna magna, tincidunt a, mattis non, imperdiet vitae, tellus. Sed odio est, auctor ac, sollicitudin in, consequat vitae, orci. Fusce id felis. Vivamus sollicitudin metus eget eros.</p></div>
</div><!-- end of row-->
</div><!-- container -->
<!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
<script src="https://code.jquery.com/jquery.js"></script>
<!-- Include all compiled plugins (below), or include individual files as needed -->
<script src="./js/bootstrap.min.js"></script>
这是我的完整代码，如果有人能指出这里有什么问题，我将不胜感激。我敢肯定这很简单。
强尼