语法高亮，滚动条美化，设置页面调整

docs/javascript/Reference/Operators/Grouping.html

@@ -4,12 +4,12 @@
 <div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/expressions-groupingoperator.html" width="100%"></iframe></div>
 <p class="hidden">这些交互的事例资源都是基于Github的仓库.如果你想提交更多的交互事例,请克隆这个url<a class="external" href="https://github.com/mdn/interactive-examples" rel="noopener">https://github.com/mdn/interactive-examples</a> 并且向我们发送合并请求</p>
 <h2 id="语法">语法</h2>
-<pre class="syntaxbox"> ( )</pre>
+<pre><code class="language-javascript"> ( )</code></pre>
 <h2 id="说明">说明</h2>
 <p>圆括号运算符由一对圆括号组成,包裹表达式和子表达式用来覆盖常规的 <a href="/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence">运算符优先级</a> ,达到低优先级的表达式比高优先级的表达式更早运算.</p>
 <h2 id="示例">示例</h2>
 <p>下面的代码展示了加法运算先于乘法运算的情况.</p>
-<pre class="brush:js">var a = 1;
+<pre><code class="language-js">var a = 1;
 var b = 2;
 var c = 3;
 
@@ -24,7 +24,7 @@ a + (b * c)   // 7
 
 // which is equivalent to
 a * c + b * c // 9
-</pre>
+</code></pre>
 <h2 id="规范">规范</h2>
 <table class="standard-table">
 <tbody>