左定宽右自适应

<div class="box">
    <div class="left"></div>
    <div class="right"></div>
</div>

1. flex布局

.box {
    width: 100%;
    height: 300px;
    border: 1px solid #ccc;
    display: flex;
}
.left {
    width: 200px;
    height: 100%;
    background-color: red;
}
.right {
    width: 100%;
    height: 100%;
    background-color:green;
    flex: 1;
}

2. BFC模式

.box {
    width: 100%;
    height: 300px;
    border: 1px solid #ccc;
}
.left {
    width: 200px;
    height: 100%;
    background-color: red;
    float: left;
}
.right {
    overflow: hidden; /* 触发bfc */
    height: 100%;
    background-color:green;
}

3. padding-left

.box {
    width: 100%;
    height: 300px;
    border: 1px solid #ccc;
}
.left {
    width: 200px;
    height: 100%;
    background-color: red;
    float: left;
}

.right {
    width: 100%;
    height: 100%;
    background-color:green;
    padding-left: 200px;
    box-sizing: border-box;
}

4. margin-left

.box {
    width: 100%;
    height: 300px;
    border: 1px solid #ccc;
}
.left{
    float:left;
    width:200px;
    height:100%;
    background:red;
}
.right{
    height:100%;        
    background:green;
    margin-left:200px;
}

5. grid

    .main{
      height: 200px;
      display: grid;
     /*分成两列*/
      grid-template-columns: minmax(200px, 25%) 1fr;
      /* 分成三列*/
      /* grid-template-columns: minmax(200px, 200px) 1fr minmax(200px, 400px);*/
    }

grid-template-columns指定页面分成两列。第一列的宽度是minmax(200px, 25%)，即最小宽度为200px，最大宽度为总宽度的25%；第二列为1fr，即所有剩余宽度。

6. calc()

.box {
    width: 100%;
    height: 300px;
    border: 1px solid #ccc;
}
.left{
    width:200px;
    height:100%;
    background:red;
    float: left;
}
.right{
    height:100%;        
    background:green;
    float: right;
    width: calc(100% - 200px);  
}

7. table布局

.box {
    width: 100%;
    height: 300px;
    border: 1px solid #ccc;
    display: table;
}
.left{
    width:200px;
    height:100%;
    background:red;
    display: table-cell;
}
.right{
    height:100%;        
    background:green;
    display: table-cell;
}

左右定宽中间自适应

1. center在right之后

<div class="box">
    <div class="left">left</div>
    <div class="right">rigth</div>
    <div class="center">center</div>
</div>

.box {
    width: 100%;
    height: 100%;
}
.left {
    float: left;
    width: 200px;
    height: 100%;
    background-color: red;
}
.right {
    float: right;
    width: 200px;
    height: 100%;
    background-color: pink;
}
.center {
    height: 100%;
    background-color: green;
}

2. div顺序正常排列使用flex布局

<div class="box">
    <div class="left">left</div>
    <div class="center">center</div>
    <div class="right">rigth</div>
</div>

.box {
  display: flex;
}
.left,
right {
  width: 200px
}
.center {
  flex: 1;
}

3. grid布局

.main {
      height: 200px;
      display: grid;
      grid-template-columns: minmax(200px, 200px) 1fr minmax(200px, 400px);
}