CSS深入理解之absolute（HTML/CSS）

本文轉載自查看原文 2017-12-30 20:34 1529

absolute和float是同父異母的兄弟，因為它們具有相同點：包裹性與破壞性

absolute的特點

1、獨立的，並且可以擺脫overflow的限制，無論是滾動還是隱藏；

2、無依賴，不受relative限制的，行為表現上是不使用top/right/bottom/left任何一個屬性或使用auto作為值；

3、脫離文檔流；

4、具有跟隨性（依據這個特點，能省很多的relative，並且擴展性更強）。

騷操作：使用注釋來消除空格

<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <title>圖標定位二三事</title>
    <style>
      body {
        font: 14px/1.4 "Microsoft YaHei";
        background-color: #EDEFF0;
      }
      body,
      h3,
      h5 {
        margin: 0;
      }
      img {
        border: 0 none;
        vertical-align: bottom;
      }
      .l {
        float: left;
      }
      .r {
        float: right;
      }
      .constr {
        width: 1200px;
        margin-left: auto;
        margin-right: auto;
      }
      .header {
        background-color: #2A2C2E;
      }
      .nav {
        height: 60px;
      }
      .nav-list {
        float: left;
        font-size: 14px;
        font-weight: 400;
      }
      .nav-a {
        display: inline-block;
        line-height: 20px;
        padding: 20px 35px;
        color: #B5BDC0;
        text-decoration: none;
      }
      .nav-a:hover {
        color: #fff;
      }
      .course {
        padding-top: 10px;
      }
      .course-list {
        float: left;
        width: 280px;
        height: 240px;
        margin: 5px 10px 15px;
        border-radius: 0 0 1px 1px;
        background-color: #F7FAF9;
        background-color: rgba(255, 255, 255, 1);
        box-shadow: 0 1px 2px #c5c5c5;
        text-decoration: none;
      }
      .course-list-img {
        background-color: #6396F1;
      }
      .course-list-h {
        line-height: 50px;
        font-size: 14px;
        font-weight: 400;
        color: #363d40;
        text-align: center;
      }
      .course-list-tips {
        margin: 0 14px;
        font-size: 12px;
        color: #b4bbbf;
        overflow: hidden;
      }
      .icon-hot {
        position: absolute;
        width: 28px;
        height: 11px;
        margin: -6px 0 0 2px;
        background: url(http://img.mukewang.com/545304730001307300280011.gif);
      }
      .icon-recom {
        position: absolute;
        line-height: 20px;
        padding: 0 5px;
        background-color: #f60;
        color: #fff;
        font-size: 12px;
      }
      .icon-vip {
        position: absolute;
        width: 36px;
        height: 36px;
        margin-left: -36px;
        background: url(http://img.mukewang.com/5453048000015d8800360036.gif);
        text-indent: -9em;
        overflow: hidden;
      }
    </style>
  </head>

  <body>
    <div class="header">
      <div class="constr">
        <div class="nav">
          <h3 class="nav-list">
                <a href="http://www.imooc.com/course/list" class="nav-a">課程</a>
            </h3>
          <h3 class="nav-list">
                <a href="http://www.imooc.com/wenda" class="nav-a">問答</a>
            </h3>
          <h3 class="nav-list">
                <a href="http://www.imooc.com/seek/index" class="nav-a">
                    求課<i class="icon-hot"></i>
                </a>
            </h3>
        </div>
      </div>
    </div>

    <div class="main">
      <div class="constr">
        <div class="course">
          <a href="http://www.imooc.com/view/121" class="course-list">
            <div class="course-list-img">
              <span class="icon-recom">推薦</span>
              <img width="280" height="160" alt="分享：CSS深入理解之float浮動" src="http://img.mukewang.com/53d74f960001ae9d06000338-300-170.jpg"><!--              
              --><i class="icon-vip">vip</i>
            </div>
            <h5 class="course-list-h">分享：CSS深入理解之float浮動</h5>
            <div class="course-list-tips">
              <span class="l">已完結</span>
              <span class="r">3514人學習</span>
            </div>
          </a>
        </div>
      </div>
    </div>
  </body>
</html>

View Code

<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <title>文本圖標對齊與定位二三事</title>
    <style>
      body {
        margin: 0;
        font: 14px/1.4 "Microsoft YaHei";
        background-color: #EDEFF0;
      }
      a {
        color: #50B6E5;
      }
      .constr {
        width: 1200px;
        margin-left: auto;
        margin-right: auto;
      }
      .regist-head {
        height: 60px;
        line-height: 60px;
        padding-left: 30px;
        background-color: #be3948;
        color: #fff;
        font-size: 18px;
      }
      .regist-body {
        min-height: 400px;
        padding: 100px 0;
        background-color: #fff;
      }
      .regist-main {
        width: 600px;
        margin-left: auto;
        margin-right: auto;
      }
      .regist-group {
        margin-top: 20px;
        overflow: hidden;
      }
      .regist-label {
        width: 70px;
        padding-top: 10px;
        float: left;
      }
      .regist-cell {
        display: table-cell;
        *display: inline-block;
      }
      .regist-input {
        height: 18px;
        line-height: 18px;
        width: 260px;
        padding: 10px 5px;
        margin: 0 10px 0 0;
        border: 1px solid #d0d6d9;
        vertical-align: top;
      }
      .regist-code-input {
        width: 130px;
      }
      .regist-btn {
        display: inline-block;
        width: 160px;
        line-height: 40px;
        background-color: #39b94e;
        color: #fff;
        text-align: center;
        text-decoration: none;
      }
      .regist-btn:hover {
        background-color: #33a646;
      }
      .icon-warn {
        display: inline-block;
        width: 20px;
        height: 21px;
        background: url(http://img.mukewang.com/5453084a00016ae300120012.gif) no-repeat center;
      }
      .regist-star {
        position: absolute;
        margin-left: -1em;
        font-family: simsun;
        color: #f30;
      }
      .regist-remark {
        position: absolute;
        line-height: 21px;
        padding-top: 9px;
        color: #666;
      }
      .regist-warn {
        padding-left: 20px;
        color: #be3948;
      }
      .regist-warn>.icon-warn {
        position: absolute;
        margin-left: -20px;
      }
    </style>
  </head>

  <body>
    <div class="constr">
      <div class="regist-head">注冊</div>
      <div class="regist-body">
        <div class="regist-main">
          <div class="regist-group">
            <label class="regist-label"><span class="regist-star">*</span>登錄郵箱</label>
            <div class="regist-cell">
              <input type="email" class="regist-input"><span class="regist-remark regist-warn">
                        <i class="icon-warn"></i>郵箱格式不准確（演示）
                    </span>
            </div>
          </div>
          <div class="regist-group">
            <label class="regist-label"><span class="regist-star">*</span>登錄密碼</label>
            <div class="regist-cell">
              <input type="password" class="regist-input"><span class="regist-remark">
                        請輸入6-16位密碼，區分大小寫，不能使用空格
                    </span>
            </div>
          </div>
          <div class="regist-group">
            <label class="regist-label"><span class="regist-star">*</span>用戶昵稱</label>
            <div class="regist-cell">
              <input type="password" class="regist-input">
            </div>
          </div>
          <div class="regist-group">
            <label class="regist-label">手機號碼</label>
            <div class="regist-cell">
              <input type="tel" class="regist-input">
            </div>
          </div>
          <div class="regist-group">
            <label class="regist-label"><span class="regist-star">*</span>驗 證 碼</label>
            <div class="regist-cell">
              <input class="regist-input regist-code-input"><img src="http://img.mukewang.com/545308540001678401500040.jpg">
            </div>
          </div>
          <div class="regist-group">
            <label class="regist-label">&nbsp;</label>
            <div class="regist-cell">
              <input type="checkbox" checked><label>我已閱讀並同意<a href="##">慕課協議</a>。</label>
              <p>
                <a href="javascript:" class="regist-btn">立即注冊</a>
              </p>
            </div>
          </div>
        </div>
      </div>
    </div>
  </body>
</html>

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z-index無依賴

1、如果只有一個絕對定位元素，自然不需要z-index，自動覆蓋普通元素；

2、如果兩個絕對定位，控制DOM流的前后順序達到需要的覆蓋效果，依然無z-index；

3、如果多個絕對定位交錯，非常非常少見，z-index：1控制；

4、如果非彈框類的絕對定位元素z-index>2，必定z-index冗余，請優化。

九宮格代碼實現

<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <title>高度自適應的九宮格效果</title>
    <style>
      html,
      body {
        height: 100%;
        margin: 0;
      }
      .page {
        position: absolute;
        left: 0;
        top: 0;
        right: 0;
        bottom: 0;
      }
      .list {
        float: left;
        height: 33.3%;
        width: 33.3%;
        position: relative;
      }
      .list:before {
        content: '';
        position: absolute;
        left: 10px;
        right: 10px;
        top: 10px;
        bottom: 10px;
        border-radius: 10px;
        background-color: #cad5eb;
      }
      .list:after {
        content: attr(data-index);
        position: absolute;
        height: 30px;
        left: 0;
        right: 0;
        top: 0;
        bottom: 0;
        margin: auto;
        text-align: center;
        font: 24px/30px bold 'microsoft yahei';
      }
    </style>
  </head>

  <body>
    <div class="page">
      <div class="list" data-index="1"></div>
      <div class="list" data-index="2"></div>
      <div class="list" data-index="3"></div>
      <div class="list" data-index="4"></div>
      <div class="list" data-index="5"></div>
      <div class="list" data-index="6"></div>
      <div class="list" data-index="7"></div>
      <div class="list" data-index="8"></div>
      <div class="list" data-index="9"></div>
    </div>
  </body>
</html>

View Code

絕對定位整頁布局演示

<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0,user-scalable=no">
    <title>慕課網-絕對定位整頁布局演示</title>
    <style>
    body {
        font-family: 'microsoft yahei';
      }
      /* wechat.css */
      
      body {
        margin: 0;
        -webkit-user-select: none;
        user-select: none;
        -ms-touch-action: none;
      }
      /* construction */
      
      html, body, .page {
        height: 100%;
        width: 100%;
        overflow: hidden;
      }
      .page {
        position: absolute;
        left: 0;
        top: 0;
      }
      body {
        background-color: #ebebeb;
        font-family: "Helvetica Neue", Helvetica, STHeiTi, sans-serif;
      }
      a {
        text-decoration: none;
        -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
      }
      h1, h2, h3, h4, h5, h6 {
        margin: 0;
        font-weight: 400;
      }
      ul, ol {
        margin: 0;
        list-style-type: none;
      }
      .header, .footer, .content {
        position: absolute;
        left: 0;
        right: 0;
      }
      .header {
        height: 48px;
        padding: 0 5px;
        background-color: #21292B;
        color: #fff;
        top: 0;
        z-index: 1;
      }
      .header>h1 {
        line-height: 48px;
        margin: 0 0 0 10px;
        font-size: 18px;
        float: left;
      }
      .header>a {
        display: inline-block;
        width: 48px;
        height: 48px;
        background-size: 48px 144px;
        text-indent: -9em;
        overflow: hidden;
      }
      .header>.icon-search, .header>.icon-add {
        float: right;
      }
      .footer {
        height: 52px;
        border-top: 1px solid #dfdfdf;
        background-color: #fcfcfc;
        bottom: 0;
        z-index: 1;
      }
      .footer>a {
        width: 25%;
        text-align: center;
        color: #999;
        float: left;
        font-size: 14px;
      }
      .footer>a>i {
        display: block;
        height: 35px;
        margin-bottom: -3px;
        background-size: 35px 280px;
      }
      .footer>.active {
        color: #45c018;
      }
      .content {
        top: 48px;
        bottom: 53px;
        overflow: auto;
      }
      .icon-search, .icon-back, .icon-add {
        background: url(http://img.mukewang.com/547d339b000188bb00960288.png) no-repeat;
      }
      .icon-back {
        background-position: 0 -96px;
      }
      .icon-add {
        background-position: 0 -48px;
      }
      .icon-wechat, .icon-contacts, .icon-finds, .icon-mes {
        background: url(http://img.mukewang.com/547d33970001444d00700560.png) no-repeat center top;
      }
      .active .icon-wechat {
        background-position: center -35px;
      }
      .icon-contacts {
        background-position: center -70px;
      }
      .active .icon-contacts {
        background-position: center -105px;
      }
      .icon-finds {
        background-position: center -140px;
      }
      .active .icon-finds {
        background-position: center -175px;
      }
      .icon-mes {
        background-position: center -210px;
      }
      .active .icon-mes {
        background-position: center -245px;
      }
      .icon-find {
        background: url(icon-find.png) no-repeat;
        background-size: 28px 210px;
      }
      .icon-find-2 {
        background-position: 0 -30px;
      }
      .icon-find-3 {
        background-position: 0 -60px;
      }
      .icon-find-4 {
        background-position: 0 -90px;
      }
      .icon-find-5 {
        background-position: 0 -120px;
      }
      .icon-find-6 {
        background-position: 0 -150px;
      }
      .icon-find-7 {
        background-position: 0 -180px;
      }
      .icon-me {
        background: url(icon-me.png) no-repeat;
        background-size: 28px 120px;
      }
      .icon-me-2 {
        background-position: 0 -30px;
      }
      .icon-me-3 {
        background-position: 0 -60px;
      }
      .icon-me-4 {
        background-position: 0 -90px;
      }
      .wechat-list {
        display: block;
        height: 64px;
        padding: 8px 12px;
        box-sizing: border-box;
        border-bottom: 1px solid #d7d7d7;
        background-color: #fff;
      }
      .wechat-list:last-child {
        border-bottom: 0;
      }
      .wechat-list>img {
        width: 48px;
        height: 48px;
        float: left;
      }
      .wechat-list>.cell {
        padding-left: 58px;
        line-height: 24px;
        color: #333;
      }
      .wechat-h-time {
        overflow: hidden;
      }
      .wechat-h-time>h5 {
        font-size: 100%;
        float: left;
      }
      .wechat-h-time>time {
        font-size: 12px;
        color: #b9b9b9;
        float: right;
      }
      .wechat-h-time .business {
        color: #54688D;
      }
      .wechat-h-time+p {
        margin: 0 20px 0 0;
        font-size: 14px;
        color: #a8a8a8;
        white-space: nowrap;
        text-overflow: ellipsis;
        overflow: hidden;
      }
      .wechat-detail {
        position: relative;
        z-index: 1;
      }
    }
    </style>
  </head>

  <body>
    <div class="page">
      <div class="header">
        <h1>慕課網</h1>
        <a href="javascript:" class="icon-add">添加</a>
        <a href="javascript:" class="icon-search">搜索</a>
      </div>
      <div class="content">
        <div class="">
          <a href="http://www.imooc.com/learn/192" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>早上09:51</time></div>
              <p>CSS深入理解值絕對定位</p>
            </div>
          </a>
          <a href="http://www.imooc.com/learn/192" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>早上09:38</time></div>
              <p>如果高度不夠，可以手動縮小瀏覽器高度</p>
            </div>
          </a>
          <a href="http://www.imooc.com/learn/192" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>早上08:47</time></div>
              <p>此demo是本系列最后一個demo</p>
            </div>
          </a>
          <a href="http://www.imooc.com/learn/192" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>早上08:36</time></div>
              <p>此demo需要在高級瀏覽器中查看</p>
            </div>
          </a>
          <a href="http://www.imooc.com/learn/192" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>昨天</time></div>
              <p>重在原理展示，結構可多變。例如，header放在page外面~~</p>
            </div>
          </a>
          <a href="https://github.com/zhangxinxu/mobilebone" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>昨天</time></div>
              <p>最近鄙人整了個名叫Mobilebone的開源項目</p>
            </div>
          </a>
          <a href="https://github.com/zhangxinxu/mobilebone" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>星期三</time></div>
              <p>就是依賴絕對定位整體布局，大家可以前去圍觀</p>
            </div>
          </a>
          <a href="http://www.imooc.com/learn/192" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5 class="business">慕課網</h5><time>星期三</time></div>
              <p><img src="http://img.mukewang.com/547d33a00001299b00320033.jpg" width="16" height="16"></p>
            </div>
          </a>
          <a href="http://www.imooc.com/learn/121" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>星期三</time></div>
              <p>CSS深入理解之浮動</p>
            </div>
          </a>
          <a href="http://www.imooc.com/learn/121" class="wechat-list">
            <img src="http://img.mukewang.com/547d338d00010ced01200120.jpg">
            <div class="cell">
              <div class="wechat-h-time">
                <h5>張鑫旭</h5><time>上周</time></div>
              <p>同樣精彩，歡迎支持~</p>
            </div>
          </a>
        </div>
      </div>

      <div class="footer">
        <a href="http://www.imooc.com/course/list">
          <i class="icon-wechat"></i>課程
        </a>
        <a href="http://www.imooc.com/wenda">
          <i class="icon-contacts"></i>問答
        </a>
        <a href="http://www.imooc.com/seek/index">
          <i class="icon-finds"></i>求課
        </a>
        <a href="http://www.imooc.com/space/course" class="active">
          <i class="icon-mes"></i>我的課程
        </a>
      </div>
    </div>
  </body>
</html>

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