左边固定，右边自适应布局(四种方法：负边距、flex)

1、左position:absolute, 右margin-left 

<div class="parent">

        <div class="l-child"></div>

        <div class="r-child"></div>

</div>

//父元素相对定位，作为子元素绝对定位的参考

.parent{display:relative;background:#ddd}

.l-child{position:absolute;width:100px;background:#bbb}

.r-child{margin-left:100px;background:#999}

2、左边float，触发父元素宽度计算 

html结构同上

.parent{background:#ddd;overflow:hidden; }

.l-child{float:left;width:100px;background:#bbb;z-index:10000; }

.r-child{margin-left:100px;background:#999;}

3、左右浮动，右边使用负边距

<div class="parent">

        <div class="l-box"></div>

        <div class="r-box">

                <div class="r-content">中文</div>

        </div>

        <div class="l-box">中文网</div>

<./div>

.parent{background:#ddd;overflow:hidden; }

.l-box{float:left;width:100px;background:#bbb;}

.r-box{float:right;width:100%;margin-left:-100px;background:#999;}

.r-content{margin-left:100px;}

4、flex布局 

父元素flex布局后，子元素默认就是弹性布局，除非你确定子元素的弹性方式

ps：这个方法完美之处还在于，垂直方向也自动填充，轻松实现了等高布局！！

html同第一个demo

.parent{display:flex;background:#ddd}

.l-child{flex:00100px;background:#bbb}

.r-child{background:#999}