用五种不同的布局方式实现“左右300px中间自适应”的效果

float浮动

<section class="layout float">
        <style media="screen">
            .layout.float .left{
                float: left;
                width: 300px;
                background: pink;
            }
            .layout.float .right{
                float: right;
                width: 300px;
                background: lightblue;
            }
            .layout.float .center {
                background: lightyellow;
            }
        </style>
        <article class="left-right-center">
            <div class="left"></div>
            <div class="right"></div>
            <div class="center">
                <h1>浮动解决方案</h1>
                1.这是三栏布局中的中间部分
                2.这是三栏布局中的中间部分
            </div>
        </article>
    </section>

absolute绝对定位

<section class="layout absolute">
        <style media="screen">
            .layout.absolute .left-right-center>div {
                position: absolute;
            }
            .layout.absolute .left {
                width: 300px;
                left: 0;
                background: lightblue;
            }
            .layout.absolute .right {
                width: 300px;
                right: 0;
                background: lightgreen;
            }
            .layout.absolute .center {
                left: 300px;
                right: 300px;
                background: pink;
            }
        </style>
        <article class="left-right-center">
            <div class="left"></div>
            <div class="right"></div>
            <div class="center">
                <h1>绝对定位解决方案</h1>
                2.这是三栏布局的中间部分
            </div>
        </article>
    </section>

flex布局

<section class="layout flexbox">
        <style media="screen">
            .layout.flexbox .left-center-right {
                margin-top: 140px;
                display: flex;
            }
            .layout.flexbox .left {
                width: 300px;
                background: lightcoral;
            }
            .layout.flexbox .center {
                flex:1;
                background: lightgray;
            }
            .layout.flexbox .center2 {
                flex:1;     /*按照数字的比例自动分配剩余空间*/
                background: lightgreen;
            }
            .layout.flexbox .right {
                width: 300px;
                background: lightblue;
            }
        </style>
        <article class="left-center-right">
            <div class="left"></div>
            <div class="center">
                <h1>flex布局解决方案</h1>
                3.这是三栏布局的中间部分
            </div>
            <div class="center2">
                <h1>flex布局解决方案</h1>
                3.这是三栏布局的中间部分
            </div>
            <div class="right"></div>
        </article>
    </section>

table布局

<section class="layout table">
        <style>
            .layout.table .left-center-right {
                width: 100%;
                height: 100px;
                display: table;
            }
            .layout.table .left-center-right>div {
                display: table-cell;
            }
            .layout.table .left {
                width: 300px;
                background: lightgreen;
            }
            .layout.table .center {
                background: pink;
            }
            .layout.table .right {
                width: 300px;
                background: lightblue;
            }
        </style>
        <article class="left-center-right">
            <div class="left"></div>
            <div class="center">
                <h1>table解决方案</h1>
                4.这是三栏布局的中间部分
            </div>
            <div class="right"></div>
        </article>
    </section>

grid网格布局

<section class="layout grid">
        <style>
            .layout.grid .left-center-right {
                display: grid;
                width: 100%;
                grid-template-rows:100px;
                grid-template-columns:300px auto 300px;
            }
            .left {
                background: lightgreen;
            }
            .center {
                background: pink;
            }
            .right {
                background: lightblue;
            }
        </style>
        <article class="left-center-right">
            <div class="left"></div>
            <div class="center">
                <h1>网格布局解决方案</h1>
                5.这是三栏布局的中间部分
            </div>
            <div class="right"></div>
        </article>
    </section>