1.hover

移入其父元素.navI時(shí)，觸發(fā)鼠標(biāo)的hover態(tài)，給父元素添加樣式為position:relative;z-index:1;。從而提升了層級z-index。在其子元素導(dǎo)航內(nèi)容的層級比拼中，“子憑父貴”，父元素層級高的，其導(dǎo)航內(nèi)容在重疊狀態(tài)中顯示在最上面

<style>
body,p{margin: 0;}
h2{margin: 0;font-size:100%;}
ul{margin: 0;padding: 0;list-style: none;}
a{text-decoration: none;color:inherit;}
.box{width: 572px;border: 1px solid #999;overflow: hidden;}
.nav{margin-left: -1px;font: 14px "微軟雅黑";overflow: hidden;background-color: #f1f1f1;}
.navI{float: left;width: 33.333%;box-sizing: border-box;}
.navI-tit{line-height: 40px;text-align: center;cursor: pointer;border-left: 1px solid #cecece;border-bottom: 1px solid #cecece;}
.navI-txt{width: 572px;height:200px;text-indent:2em;line-height: 2;background:#fff;}
.ml1{margin-left: -100%;}
.ml2{margin-left: -200%;}
.navI_active{position:relative;z-index:1;}
/*重點(diǎn)代碼*/
.navI:hover{position:relative;z-index:1;}
.navI:hover .navI-tit{background:#fff;border-bottom:none;}
</style>
<div class="box">
<ul class="nav">
<li class="navI navI_active">
<h2 class="navI-tit">課程</h2>
<p class="navI-txt">課程內(nèi)容</p>
</li>
<li class="navI">
<h2 class="navI-tit">學(xué)習(xí)計(jì)劃</h2>
<p class="navI-txt ml1">學(xué)習(xí)計(jì)劃內(nèi)容</p>
</li>
<li class="navI">
<h2 class="navI-tit">技能圖譜</h2>
<p class="navI-txt ml2">技能圖譜內(nèi)容</p>
</li>
</ul>
</div>

2.錨點(diǎn)

點(diǎn)擊導(dǎo)航標(biāo)題時(shí)，觸發(fā)target偽類，改變對應(yīng)的導(dǎo)航內(nèi)容的層級z-index，從而使當(dāng)前導(dǎo)航內(nèi)容在三個(gè)導(dǎo)航內(nèi)容中勝出，在最上層顯示；與此同時(shí)，改變當(dāng)前導(dǎo)航標(biāo)題的樣式

<style>
body,p{margin: 0;}
h2{margin: 0;font-size:100%;}
ul{margin: 0;padding: 0;list-style: none;}
a{text-decoration: none;color:inherit;}
.box{width: 572px;border: 1px solid #999;overflow: hidden;}
.nav{margin-left: -1px;font: 14px "微軟雅黑";overflow: hidden;background-color: #f1f1f1;}
.navI{float: left;width: 33.333%;box-sizing: border-box;position:relative;}
.navI-tit{position:absolute;top:0;left:0;right:0;box-sizing: border-box;line-height: 40px;height: 40px;text-align: center;cursor: pointer;border-left: 1px solid #cecece;border-bottom: 1px solid #cecece;}
.navI-txt{width: 572px;height:200px;margin-top: 40px;text-indent:2em;line-height: 2;background:#fff;}
.ml1{margin-left: -100%;}
.ml2{margin-left: -200%;}