我是Dart和Polymer的新手。我正在尝试创建选项卡，但它们无法正确显示。这是我的代码：
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="scaffolded-by" content="https://github.com/google/stagehand">
<title>Paper Tabs Events</title>
<link rel="stylesheet" href="styles.css">
<link rel="import" href="packages/polymer/polymer.html">
<link rel="import" href="packages/paper_elements/roboto.html">
<link rel="import" href="packages/core_elements/core_header_panel.html">
<link rel="import" href="packages/core_elements/core_toolbar.html">
<link rel="import" href="packages/core_elements/core_pages.html">
<link rel="import" href="packages/paper_elements/paper_tabs.html">
<link rel="import" href="packages/paper_elements/paper_icon_button.html">
</head>
<body unresolved>
<core-header-panel flex>
<core-toolbar class="medium-tall">
<paper-icon-button id="navicon" icon="dashboard"></paper-icon-button>
<span flex>Main Heading</span>
<paper-icon-button id="morebutton" icon="more-vert"></paper-icon-button>
<paper-tabs class="bottom fit" selected="1">
<paper-tab>IMPORT</paper-tab>
<paper-tab>DEFINE</paper-tab>
<paper-tab>DESIGN</paper-tab>
<paper-tab>DEVELOP</paper-tab>
<paper-tab>DEPLOY</paper-tab>
<paper-tab>EXPORT</paper-tab>
</paper-tabs>
</core-toolbar>
<core-pages>
<div><h1>Core Page</h1><p>This is content for core page.</p></div>
</core-pages>
</core-header-panel>
<script type="application/dart">export 'package:polymer/init.dart';</script>
</body>
一旦它们正确显示，我就想动态更改选项卡选择选项卡上的内容。但那是以后的事了，首先选项卡需要正确显示。任何帮助将不胜感激。
这是截图它的外观。
https://www.dropbox.com/s/px2as8lor4a67ro/Screenshot%202015-04-23%2022.59.47.png?dl=0
核心标题面板的父元素需要高度（在本例中为 body）。
有关详细信息，请参阅 https://www.polymer-project.org/0.5/docs/elements/core-header-panel.html。
TLDR;您可以将"垂直全出血布局"作为身体的属性添加。