代码示例:(标识:css_form_width)
<!DOCTYPE html>
<html>
<head>
<style> 
input {
  width: 100%;
}
</style>
</head>
<body>

<p>全宽的输入字段:</p>

<form>
  <label for="fname">First Name</label>
  <input type="text" id="fname" name="fname">
</form>

</body>
</html>
运行结果: