学习聚合物的布局，纸张图标按钮在应用程序工具栏区域中不可见，代码为 '
<!-- sample-content included for demo purposes only -->
<link rel="import" href="app-layout/demo/sample-content.html">
<link rel="import" href="iron-icon/iron-icon.html">
<link rel="import" href="paper-styles/paper-styles.html">
<link rel="import" href="paper-icon-button/paper-icon-button.html">
<style is="custom-style">
body {
/* No margin on body so toolbar can span the screen */
margin: 0;
}
app-toolbar {
/* Toolbar is the main header, so give it some color */
background-color: #1E88E5;
font-family: 'Roboto', Helvetica, sans-serif;
color: white;
--app-toolbar-font-size: 24px;
}
</style>
</head>
<body>
<app-toolbar>
<paper-icon-button icon="menu"></paper-icon-button>
<div title>Spork</div>
<paper-icon-button icon="search"></paper-icon-button>
</app-toolbar>
</body>`
2，知道为什么吗？谢谢
正确的输出应该是：[带按钮的应用程序工具栏][3]
巴迪·
您缺少包含search和menu图标的iron-icons导入。包括这个应该可以解决您的问题<link rel="import" href="iron-icons/iron-icons.html">
<base href="https://polygit.org/components/">
<link rel="import" href="app-layout/demo/sample-content.html">
<link rel="import" href="iron-icon/iron-icon.html">
<link rel="import" href="iron-icons/iron-icons.html">
<link rel="import" href="paper-styles/paper-styles.html">
<link rel="import" href="paper-icon-button/paper-icon-button.html">
<style is="custom-style">
body {
/* No margin on body so toolbar can span the screen */
margin: 0;
}
app-toolbar {
/* Toolbar is the main header, so give it some color */
background-color: #1E88E5;
font-family: 'Roboto', Helvetica, sans-serif;
color: white;
--app-toolbar-font-size: 24px;
}
</style>
</head>
<body>
<app-toolbar>
<paper-icon-button icon="menu"></paper-icon-button>
<div title>Spork</div>
<paper-icon-button icon="search"></paper-icon-button>
</app-toolbar>
</body>