How to append a piece of html to the body tag #505

private static final String html = "<pre class=\"language-html\"><code><span class=\"token tag\"><span class=\"token tag\"><span class=\"token punctuation\">&lt;</span>link</span> <span class=\"token attr-name\">href</span><span class=\"token attr-value\"><span class=\"token punctuation attr-equals\">=</span><span class=\"token punctuation\">\"</span>https://unpkg.com/@wangeditor/editor@latest/dist/css/style.css<span class=\"token punctuation\">\"</span></span> <span class=\"token attr-name\">rel</span><span class=\"token attr-value\"><span class=\"token punctuation attr-equals\">=</span><span class=\"token punctuation\">\"</span>stylesheet<span class=\"token punctuation\">\"</span></span><span class=\"token punctuation\">&gt;</span></span>\n" +
            "<span class=\"token tag\"><span class=\"token tag\"><span class=\"token punctuation\">&lt;</span>style</span><span class=\"token punctuation\">&gt;</span></span><span class=\"token style\"><span class=\"token language-css\">\n" +
            "  <span class=\"token selector\">#editor—wrapper</span> <span class=\"token punctuation\">{</span>\n" +
            "    <span class=\"token property\">border</span><span class=\"token punctuation\">:</span> 1px solid #ccc<span class=\"token punctuation\">;</span>\n" +
            "    <span class=\"token property\">z-index</span><span class=\"token punctuation\">:</span> 100<span class=\"token punctuation\">;</span> <span class=\"token comment\">/* 按需定义 */</span>\n" +
            "  <span class=\"token punctuation\">}</span>\n" +
            "  <span class=\"token selector\">#toolbar-container</span> <span class=\"token punctuation\">{</span> <span class=\"token property\">border-bottom</span><span class=\"token punctuation\">:</span> 1px solid #ccc<span class=\"token punctuation\">;</span> <span class=\"token punctuation\">}</span>\n" +
            "  <span class=\"token selector\">#editor-container</span> <span class=\"token punctuation\">{</span> <span class=\"token property\">height</span><span class=\"token punctuation\">:</span> 500px<span class=\"token punctuation\">;</span> <span class=\"token punctuation\">}</span>\n" +
            "</span></span><span class=\"token tag\"><span class=\"token tag\"><span class=\"token punctuation\">&lt;/</span>style</span><span class=\"token punctuation\">&gt;</span></span>\n" +
            "</code></pre>";

    @Test
    public void t1() {
        try (final WebClient webClient = new WebClient(BrowserVersion.CHROME)) {
            HtmlPage page = webClient.getPage("https://www.xuchengen.cn/select.html");
            page.appendChild(...);// html insert body?
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }