<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>左边固定宽度，右边自适应布局</title>
<style>
.form-wap{
position: relative;
}
.form-left{
position: absolute;
top: 0;
left: 0;
width: 100px;
}
.form-right{
margin-left: 100px;
}
.form-right>input{
width: 100%;
}
</style>
</head>
<body>
<form action="" class="form-wap">
<label for="" class="form-left">姓名</label>
<div class="form-right">
<input type="text">
</div>
</form>
</body>
</html>