Bootstrap3基础教程 02 网格布局

Bootstrap 提供了一套响应式、移动设备优先的流式网格系统，随着屏幕或视口（viewport）尺寸的增加，系统会自动分为最多列。

网页设计中的网格布局作用：组织内容，让网站易于浏览，并降低用户端的负载。

Grid System

Bootstrap 包含了一个响应式的、移动设备优先的、不固定的网格系统，可以随着设备或视口大小的增加而适当地扩展到 12 列。它包含了用于简单的布局选项的预定义类，也包含了用于生成更多语义布局的功能强大的混合类。

移动设备优先策略：

1.基础的 CSS 是移动设备优先，媒体查询是针对于平板电脑、台式电脑。

2.随着屏幕大小的增加而添加元素。

3.优先设计更小的宽度。

Grid System 工作原理

1.行必须放置在 .container class 内，以便获得适当的对齐（alignment）和内边距（padding）。

2.使用行来创建列的水平组。

3.内容应该放置在列内，且唯有列可以是行的直接子元素。

4.预定义的网格类，比如 .row 和 .col-xs-4，可用于快速创建网格布局。LESS 混合类可用于更多语义布局。

5.列通过内边距（padding）来创建列内容之间的间隙。该内边距是通过 .rows 上的外边距（margin）取负，表示第一列和最后一列的行偏移。

6.网格系统是通过指定您想要横跨的十二个可用的列来创建的。例如，要创建三个相等的列，则使用三个 .col-xs-4。

媒体查询

媒体查询是非常别致的"有条件的 CSS 规则"。它只适用于一些基于某些规定条件的 CSS。如果满足那些条件，则应用相应的样式。

/* 超小设备（手机，小于 768px） */

/* Bootstrap 中默认情况下没有媒体查询 */

/* 小型设备（平板电脑，768px 起） */

@media (min-width: @screen-sm-min) { ... }

/* 中型设备（台式电脑，992px 起） */

@media (min-width: @screen-md-min) { ... }

/* 大型设备（大台式电脑，1200px 起） */

@media (min-width: @screen-lg-min) { ... }

有时候也会在媒体查询代码中包含 max-width，从而将 CSS 的影响限制在更小范围的屏幕大小之内。

@media (max-width: @screen-xs-max) { ... }

@media (min-width: @screen-sm-min) and (max-width: @screen-sm-max) { ... }

@media (min-width: @screen-md-min) and (max-width: @screen-md-max) { ... }

@media (min-width: @screen-lg-min) { ... }

网格选项

.col-xs- 超小设备手机（<768px）

.col-sm- 小型设备平板电脑（≥768px）

.col-md- 中型设备台式电脑（≥992px）

.col-lg- 大型设备台式电脑（≥1200px）

代码

01 页面居中显示的容器

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8">

    <meta http-equiv="X-UA-Compatible" content="IE=edge"><!--告诉IE浏览器用最新的引擎-->

    <meta name="viewport" content="width=device-width, initial-scale=1"><!--响应式布局-->

    <link href="bootstrap/css/bootstrap.min.css" rel="stylesheet" /><!--bootstrap样式-->

    <title></title>

</head>

<body>

    <div class="container">

        <h1 class="page-header">主体</h1>

        <p>Use this document as a way to quickly start any new project.

        All you get is this text and a mostly barebones HTML document.</p>

    </div>

    <script src="Script/jquery-1.8.3.js"></script><!--Bootstrap 的所有 JavaScript 插件都依赖 jQuery，所以必须放在前边-->

    <script src="bootstrap/js/bootstrap.min.js"></script><!--Bootstrap 的所有 JavaScript 插件-->

</body>

</html>

class：page-header，container

.page-header {

  padding-bottom: 9px;

  margin: 40px 0 20px;

  border-bottom: 1px solid #eee;

}

.container {

  padding-right: 15px;

  padding-left: 15px;

  margin-right: auto;

  margin-left: auto;

}

@media (min-width: 768px) {

  .container {

    width: 750px;

  }

}

@media (min-width: 992px) {

  .container {

    width: 970px;

  }

}

@media (min-width: 1200px) {

  .container {

    width: 1170px;

  }

}

02 网格类

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8">

    <meta http-equiv="X-UA-Compatible" content="IE=edge">

    <meta name="viewport" content="width=device-width, initial-scale=1">

    <link href="bootstrap/css/bootstrap.min.css" rel="stylesheet" />

    <title></title>

</head>

<body>

    <div class="container">

        <div class="row">

            <!--

                col-lg-6 >=1200px

                col-md-8 >=992px

                col-sm-6 >=768px

                col-xs-6 <798px

            -->

            <div class="col-md-8 col-sm-6">

                <h1 class="page-header">主体</h1>

                <p>

                    Use this document as a way to quickly start any new project.

                    All you get is this text and a mostly barebones HTML document.

                </p>

            </div>

            <div class="col-md-4 col-sm-6">

                <h1 class="page-header">边栏</h1>

                <p>

                    Use this document as a way to quickly start any new project.

                    All you get is this text and a mostly barebones HTML document.

                </p>

            </div>

        </div>

    </div>

    <script src="Script/jquery-1.8.3.js"></script>

    <script src="bootstrap/js/bootstrap.min.js"></script>

</body>

</html>

03 混合使用网格类

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8">

    <meta http-equiv="X-UA-Compatible" content="IE=edge">

    <meta name="viewport" content="width=device-width, initial-scale=1">

    <link href="bootstrap/css/bootstrap.min.css" rel="stylesheet" />

    <title></title>

</head>

<body>

    <div class="container">

        <div class="row">

            <!--

                col-lg-6 >=1200px

                col-md-8 >=992px

                col-sm-6 >=768px

                col-xs-6 <798px

            -->

            <div class="col-md-9 col-sm-8 col-xs-6 col-lg-10">

                <h1 class="page-header">主体</h1>

                <p>

                    Use this document as a way to quickly start any new project.

                    All you get is this text and a mostly barebones HTML document.

                </p>

            </div>

            <div class="col-md-3 col-sm-4 col-xs-6 col-lg-2">

                <h1 class="page-header">边栏</h1>

                <p>

                    Use this document as a way to quickly start any new project.

                    All you get is this text and a mostly barebones HTML document.

                </p>

            </div>

        </div>

    </div>

    <script src="Script/jquery-1.8.3.js"></script>

    <script src="bootstrap/js/bootstrap.min.js"></script>

</body>

</html>

04 push和pull

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8">

    <meta http-equiv="X-UA-Compatible" content="IE=edge">

    <meta name="viewport" content="width=device-width, initial-scale=1">

    <link href="bootstrap/css/bootstrap.min.css" rel="stylesheet" />

    <title></title>

</head>

<body>

    <div class="container">

        <div class="row">

            <div class="col-md-9 col-md-push-3"><!--col-md-push-3：中等尺寸往右推3个网格-->

                <h1 class="page-header">主体</h1>

                <p>

                    Use this document as a way to quickly start any new project.

                    All you get is this text and a mostly barebones HTML document.

                </p>

            </div>

            <div class="col-md-3 col-md-pull-9"><!--col-md-pull-9:中等尺寸往左拉9个网格-->

                <h1 class="page-header">边栏</h1>

                <p>

                    Use this document as a way to quickly start any new project.

                    All you get is this text and a mostly barebones HTML document.

                </p>

            </div>

        </div>

    </div>

    <script src="Script/jquery-1.8.3.js"></script>

    <script src="bootstrap/js/bootstrap.min.js"></script>

</body>

</html>

05 嵌套的布局

class:clearfix 清除浮动 or 每行网格都放在 class:row中的div中

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8">

    <meta http-equiv="X-UA-Compatible" content="IE=edge">

    <meta name="viewport" content="width=device-width, initial-scale=1">

    <link href="bootstrap/css/bootstrap.min.css" rel="stylesheet" />

    <title></title>

</head>

<body>

    <div class="container">

        <div class="row">

            <div class="col-md-8">

                <h1 class="page-header">主体</h1>

                <p>

                    Use this document as a way to quickly start any new project.

                    All you get is this text and a mostly barebones HTML document.

                </p>

                <div class="row">

                    <div class="col-md-4">

                        <h1 class="page-header">区块1</h1>

                        <p>

                            Use this document as a way to quickly start any new project.

                            All you get is this text and a mostly barebones HTML document.

                            Use this document as a way to quickly start any new project.

                            All you get is this text and a mostly barebones HTML document.

                            Use this document as a way to quickly start any new project.

                            All you get is this text and a mostly barebones HTML document.

                            Use this document as a way to quickly start any new project.

                            All you get is this text and a mostly barebones HTML document.

                        </p>

                    </div>

                    <div class="col-md-4">

                        <h1 class="page-header">区块2</h1>

                        <p>

                            Use this document as a way to quickly start any new project.

                            All you get is this text and a mostly barebones HTML document.

                        </p>

                    </div>

                    <div class="col-md-4">

                        <h1 class="page-header">区块3</h1>

                        <p>

                            Use this document as a way to quickly start any new project.

                            All you get is this text and a mostly barebones HTML document.

                        </p>

                    </div>

                    <div class="clearfix"></div>

                    <div class="col-md-6">

                        <h1 class="page-header">区块4</h1>

                        <p>

                            Use this document as a way to quickly start any new project.

                            All you get is this text and a mostly barebones HTML document.

                        </p>

                    </div>

                    <div class="col-md-6">

                        <h1 class="page-header">区块5</h1>

                        <p>

                            Use this document as a way to quickly start any new project.

                            All you get is this text and a mostly barebones HTML document.

                        </p>

                    </div>

                </div>

            </div>

            <div class="col-md-4">

                <h1 class="page-header">边栏</h1>

                <p>

                    Use this document as a way to quickly start any new project.

                    All you get is this text and a mostly barebones HTML document.

                </p>

            </div>

        </div>

    </div>

    <script src="Script/jquery-1.8.3.js"></script>

    <script src="bootstrap/js/bootstrap.min.js"></script>

</body>

</html>