理解僞元素 :before 和 :after

時間 2021-01-04

原文原文鏈接

層疊樣式表（CSS）的主要目的是給HTML元素添加樣式，然而，在一些案例中給文檔添加額外的元素是多餘的或是不可能的。事實上CSS中有一個特性允許我們添加額外元素而不擾亂文檔本身，這就是「僞元素」。你一定聽說過這個詞，尤其是當你一直關注着我們的教程。點此瀏覽原作者的其他文章事實上，的確有一些CSS家族的成員（CSS選擇器）被分類爲僞元素比如：:first-line, :first-letter,

>>阅读原文<<

1. 對僞元素::after和::before的理解
2. 理解僞元素 :Before 和 :After
3. 理解:Before和:After僞元素
4. 理解僞元素 :before 和 :after
5. 僞元素 before after
6. 僞元素::after和::before
7. before和：after僞元素
8. ::before 和 ::after 僞元素
9. css僞元素after、before
10. css僞元素 ::after ::before
更多相關文章...
• RSS , <link>, 和 <description> 元素</a> - <a href="http://www.voidme.com/rss" target="_blank" title="RSS 教程"> RSS 教程</a></li> <li> • <a href="http://www.voidme.com/rss/rss-tag-title-link-description-channel" target="_blank" title="RSS <title>, <link>, 和 <description> 元素"> RSS <title>, <link>, 和 <description> 元素</a> - <a href="http://www.voidme.com/rss" target="_blank" title="RSS 教程"> RSS 教程</a></li> <li> • <a href="http://www.voidme.com/content/zzbbjljccb-bsx" target="_blank" title="Docker 清理命令"> Docker 清理命令</a> </li> <li> • <a href="http://www.voidme.com/content/kzhcgkljmp-bsx" target="_blank" title="適用於PHP初學者的學習線路和建議"> 適用於PHP初學者的學習線路和建議</a> </li> </ul> <div class="margin-top-20"></div> <div> <div></div> </div> <div class="margin-top-20"></div> <div class="relative">相關標籤/搜索</div> <ul> <a target='_blank' href="http://hk.javashuo.com/tag/before%26after" title="before&after"> <span class="new-label">before&after</span></a> <a target='_blank' href="http://hk.javashuo.com/tag/%E5%85%83%E7%B4%A0" title="元素"> <span class="new-label">元素</span></a> <a target='_blank' href="http://hk.javashuo.com/tag/%E5%83%9E%E9%A1%9E%2F%E5%85%83%E7%B4%A0%E9%81%B8%E6%93%87%E5%99%A8" title="僞類/元素選擇器"> <span class="new-label">僞類/元素選擇器</span></a> <a target='_blank' href="http://hk.javashuo.com/tag/%E8%A7%A3%E5%85%83" title="解元"> <span class="new-label">解元</span></a> <a target='_blank' href="http://hk.javashuo.com/tag/%E8%A7%A3%E5%92%8C" title="解和"> <span class="new-label">解和</span></a> <a target='_blank' href="http://hk.javashuo.com/tag/%E5%92%8C%E8%A7%A3" title="和解"> <span class="new-label">和解</span></a> <a target='_blank' href="http://hk.javashuo.com/tag/%E5%BE%AE%E9%87%8F%E5%85%83%E7%B4%A0" title="微量元素"> <span class="new-label">微量元素</span></a> <a target='_blank' href="http://hk.javashuo.com/tag/%E5%85%83%E7%B4%A0%E7%AC%A6%E8%99%9F" title="元素符號"> <span class="new-label">元素符號</span></a> <a href="http://www.voidme.com/xlink" target="_blank" title="XLink 和 XPointer 教程"> <span class="new-label">XLink 和 XPointer 教程</span></a> <a href="http://www.voidme.com/mybatis" target="_blank" title="MyBatis教程"> <span class="new-label">MyBatis教程</span></a> <a href="http://www.voidme.com/nosql" target="_blank" title="NoSQL教程"> <span class="new-label">NoSQL教程</span></a> </ul> </div> <div class="article_social"> <div class="article_like"> <div class="circle circle-like" id="my_zan" data_id="eEvIVb6"></div> </div> <div class="clear"></div> <div class="share"> <span class="share-left bdsharebuttonbox" data-tag="share_1"> <a href="#" class="bds_more icon-share" data-cmd="more"> <span class="bds_count" data-cmd="count" title="累计分享0次">0</span> </a> </span> <div class="share-right action action-share bdsharebuttonbox" data-tag="share_1"> <span class="bdshare"> <a href="#" class="bds_sinaweibo icon-weibo" data-cmd="tsina" title="分享到新浪微博">分享到微博</a> <a href="#" class="bds_weixin icon-wechat" data-cmd="weixin" title="分享到微信">分享到微信</a> <a href="#" class="bds_qq icon-qq" data-cmd="sqq" title="分享到QQ好友">分享到QQ</a> </span> </div> </div> <div class="clear"></div> <div class="bottom_plink huodong-detail-plink-banner clearfix"> </div> </div> <script> $(function () { $("#originfo").text("https://blog.csdn.net/weixin_33898233/article/details/93233041"); $("#originfo").hover(function () { $("#originfo").attr("href", "/link?url=https://blog.csdn.net/weixin_33898233/article/details/93233041"); }, function () { $("#originfo").attr("href", "javascript:void()"); }); }); </script> <script src="http://static2.javashuo.com/static/script/article.js?time=1735430479762" type="text/javascript"></script> </div> <div class="span3 article_right_side"> <div class="right_top"> <div id="right_site_articles" class="article_detail_bg"> <div class="article-part-title"> <span>每日一句</span> </div> <ul class="side_article_list"> 每一个你不满意的现在，都有一个你没有努力的曾经。 </ul> </div><script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>  <ins class="adsbygoogle" style="display:block" data-ad-client="ca-pub-6208739752673518" data-ad-slot="5830279121" data-ad-format="auto" data-full-width-responsive="true"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> <div id="right_site_articles"> <div class="article-part-title"> <span>最新文章</span> </div> <ul class="side_article_list"> <li class="side_article_list_item">1. <a href="http://hk.javashuo.com/article/p-vteahqvq-xh.html" target="_blank" title="gitlab新建分支後，android studio拿不到"> gitlab新建分支後，android studio拿不到 </a> </li> <li class="side_article_list_item">2. <a href="http://hk.javashuo.com/article/p-hppexfwt-xh.html" target="_blank" title="Android Wi-Fi 連接/斷開時間"> Android Wi-Fi 連接/斷開時間 </a> </li> <li class="side_article_list_item">3. <a href="http://hk.javashuo.com/article/p-xyczpsbi-xh.html" target="_blank" title="今日頭條面試題+答案，花點時間看看！"> 今日頭條面試題+答案，花點時間看看！ </a> </li> <li class="side_article_list_item">4. <a href="http://hk.javashuo.com/article/p-tbrvxxih-xh.html" target="_blank" title="小程序時間組件的開發"> 小程序時間組件的開發 </a> </li> <li class="side_article_list_item">5. <a href="http://hk.javashuo.com/article/p-wclmcntc-xh.html" target="_blank" title="小程序學習系列一"> 小程序學習系列一 </a> </li> <li class="side_article_list_item">6. <a href="http://hk.javashuo.com/article/p-qlpvkiub-xh.html" target="_blank" title="[微信小程序] 微信小程序學習(一)——起步"> [微信小程序] 微信小程序學習(一)——起步 </a> </li> <li class="side_article_list_item">7. <a href="http://hk.javashuo.com/article/p-nfknntlf-xh.html" target="_blank" title="硬件"> 硬件 </a> </li> <li class="side_article_list_item">8. <a href="http://hk.javashuo.com/article/p-pxyetscn-xh.html" target="_blank" title="C3盒模型以及他出現的必要性和圓角邊框/前端三"> C3盒模型以及他出現的必要性和圓角邊框/前端三 </a> </li> <li class="side_article_list_item">9. <a href="http://hk.javashuo.com/article/p-dufnxewo-xh.html" target="_blank" title="DELL戴爾筆記本關閉觸摸板觸控板WIN10"> DELL戴爾筆記本關閉觸摸板觸控板WIN10 </a> </li> <li class="side_article_list_item">10. <a href="http://hk.javashuo.com/article/p-uibznwhq-xh.html" target="_blank" title="Java的long和double類型的賦值操作爲什麼不是原子性的？"> Java的long和double類型的賦值操作爲什麼不是原子性的？ </a> </li> </ul> </div> </div> <div class="operate_zone"> <div id="right_site_articles" class="article_detail_bg margin-top10"> <div class="article-part-title"> <span><a href="/contact" target="_blank">本站公眾號</a></span> </div> <div class="side_article_list user-head"> <span style="color: #5ba607;font-size:14px;"> 歡迎關注本站公眾號,獲取更多信息</span><br/> <img src="http://open.weixin.qq.com/qr/code?username=develong"/> </div> </div> <div id="right_site_articles"> <div class="article-part-title"> <span>相關文章</span> </div> <ul class="side_article_list"> <li class="side_article_list_item">1. <a href="http://hk.javashuo.com/article/p-powqrhel-u.html" target="_blank" title="對僞元素::after和::before的理解"> 對僞元素::after和::before的理解 </a> </li> <li class="side_article_list_item">2. <a href="http://hk.javashuo.com/article/p-otfkbmyv-e.html" target="_blank" title="理解僞元素 :Before 和 :After"> 理解僞元素 :Before 和 :After </a> </li> <li class="side_article_list_item">3. <a href="http://hk.javashuo.com/article/p-hipoucli-g.html" target="_blank" title="理解:Before和:After僞元素"> 理解:Before和:After僞元素 </a> </li> <li class="side_article_list_item">4. <a href="http://hk.javashuo.com/article/p-uvlfdlig-g.html" target="_blank" title="理解僞元素 :before 和 :after"> 理解僞元素 :before 和 :after </a> </li> <li class="side_article_list_item">5. <a href="http://hk.javashuo.com/article/p-hgjsbthh-ec.html" target="_blank" title="僞元素 before after"> 僞元素 before after </a> </li> <li class="side_article_list_item">6. <a href="http://hk.javashuo.com/article/p-chzrwcot-gp.html" target="_blank" title="僞元素::after和::before"> 僞元素::after和::before </a> </li> <li class="side_article_list_item">7. <a href="http://hk.javashuo.com/article/p-sszcdtgo-go.html" target="_blank" title="before和：after僞元素"> before和：after僞元素 </a> </li> <li class="side_article_list_item">8. <a href="http://hk.javashuo.com/article/p-pkjcuhrg-gc.html" target="_blank" title="::before 和 ::after 僞元素"> ::before 和 ::after 僞元素 </a> </li> <li class="side_article_list_item">9. <a href="http://hk.javashuo.com/article/p-alwthhzn-qz.html" target="_blank" title="css僞元素after、before"> css僞元素after、before </a> </li> <li class="side_article_list_item">10. <a href="http://hk.javashuo.com/article/p-mghaxgpy-gb.html" target="_blank" title="css僞元素 ::after ::before"> css僞元素 ::after ::before </a> </li> </ul> <div style='padding-left:10px;font-size:14px;padding-bottom:10px;'> <a href='http://hk.javashuo.com/relative/p-rprlhkfn-qz.html' target='_blank' title="理解僞元素 :before 和 :after 的相關文章"> >>更多相關文章<< </a> </div> </div> </div> </div> </div> <script type="text/javascript"> $('table').each(function (i) { var size = $(this).children().size(); if (size > 1) { $(this).attr('class', "table table-bordered"); } else if (size == 1) { var e11 = $(this).children(":first"); var e1 = e11[0]; var name = e1.nodeName.toLowerCase(); if ("tbody" == name) { if (e1.children.length > 1) { $(this).attr('class', "table table-bordered"); } else if (e1.children.length == 1) { var e12 = e1.children[0]; var name2 = e12.nodeName.toLowerCase(); if ("tr" == name2) { if (e12.children.length > 1) { $(this).attr('class', "table table-bordered"); } } } } } }); window.page = 0; window.last = 0; window.first = true; resize_article_image('#nei', 550); + (function($){ window._bd_share_config = { common: { "bdText": "【" + $("title").text() + "】" + $(".post-content p:lt(2)").text(), "bdMini": "2", "bdMiniList": false, "bdPic": $(".post-content img:first") ? $(".post-content img:first").attr("src") : "", "bdStyle": "0", "bdSize": "24" }, share: [{ bdCustomStyle: 'http://static2.javashuo.com/static/css/share.css' }], }; with(document) 0[(getElementsByTagName("head")[0] || body).appendChild(createElement("script")).src = "http://bdimg.share.baidu.com/static/api/js/share.js?cdnversion=" + ~ ( - new Date() / 36e5)]; })(window.jQuery); </script> </div> <script type="text/javascript" src="http://static2.javashuo.com/static/plugin/highlight/highlight.pack.js"></script> <link href="http://static2.javashuo.com/static/plugin/highlight/styles/docco.css" media="screen" rel="stylesheet" type="text/css" /> <script type="text/javascript"> $('pre').each(function(i, e) { hljs.highlightBlock(e, "<span class='indent'> </span>", false) }); </script> <div class="footer"> <div class="footer-inner" style="padding-top: 50px;padding-bottom: 50px"> <a href="http://hk.javashuo.com/contact" target="_blank">聯繫我們</a> <a href="http://hk.javashuo.com/search">最近搜索</a> <a href="http://hk.javashuo.com/recent">最新文章</a> <script type="text/javascript" src="https://v1.cnzz.com/z_stat.php?id=1279585947&web_id=1279585947"></script> <a href="https://beian.miit.gov.cn/" target="_blank">沪ICP备13005482号-10</a> <a href="http://www.voidme.com/mybatis" target="_blank">MyBatis教程</a> <a href="http://www.voidme.com/sql" target="_blank">SQL 教程</a> <a href="http://www.voidme.com/mysql" target="_blank">MySQL教程</a> <a href="http://www.voidme.com/java" target="_blank">Java 教程</a> <a href="http://www.voidme.com/thymeleaf" target="_blank">Thymeleaf 教程</a> <a href="http://www.voidme.com/hibernate" target="_blank">Hibernate教程</a> <a href="http://www.voidme.com/spring" target="_blank">Spring教程 </a> <a href="http://www.voidme.com/redis" target="_blank">Redis教程 </a> </div> <div style="display:none;"> <script> var _hmt = _hmt || []; (function() { var hm = document.createElement("script"); hm.src = "https://hm.baidu.com/hm.js?2936bf9a19a3d5abb5c9c726af070b7c"; var s = document.getElementsByTagName("script")[0]; s.parentNode.insertBefore(hm, s); })(); </script> </div> </div> <script type="text/javascript" src="http://static2.javashuo.com/static/script/tip.js?time=1735430479762" async></script> </body> </html>