语法高亮，滚动条美化，设置页面调整

docs/javascript/Reference/Global_Objects/Map/clear.html

@@ -4,13 +4,13 @@
 <div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/map-prototype-clear.html" width="100%"></iframe></div>
 <p class="hidden">The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone <a class="external" href="https://github.com/mdn/interactive-examples" rel="noopener">https://github.com/mdn/interactive-examples</a> and send us a pull request.</p>
 <h2 id="语法">语法</h2>
-<pre class="syntaxbox"><code><em>myMap</em>.clear();</code>
-</pre>
+<pre><code class="language-javascript"><code><em>myMap</em>.clear();</code>
+</code></pre>
 <h3 id="返回值">返回值</h3>
 <p><a href="Reference/Global_Objects/undefined" title="undefined是全局对象的一个属性。也就是说，它是全局作用域的一个变量。undefined的最初值就是原始数据类型undefined。"><code>undefined</code></a>.</p>
 <h2 id="示例">示例</h2>
 <h3 id="调用clear方法">调用<code>clear</code>方法</h3>
-<pre class="brush: js">var myMap = new Map();
+<pre><code  class="language-javascript">var myMap = new Map();
 myMap.set("bar", "baz");
 myMap.set(1, "foo");
 
@@ -21,7 +21,7 @@ myMap.clear();
 
 myMap.size;       // 0
 myMap.has("bar")  // false
-</pre>
+</code></pre>
 <h2 id="规范">规范</h2>
 <table class="standard-table">
 <tbody>