代码语言：javascript复制
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
input[type="number"]:in-range
{
border: 1px solid red;
}
input[type="number"]:out-of-range
{
border: 1px solid yellow;
}
</style>
</head>
<body>
<form>
用户名:<input type="text" name="username" id="" placeholder="请输入" required="required" ><br>
密码:<input type="password" name="password" id="" required="required" placeholder="你输入"><br>
邮箱:<input type="text" name="email" id="" required="required" placeholder="请输入"><br>
年龄:<input type="text" name="age" id="" placeholder="输入"><br>
性别:<input type="radio" name="sex" id="" value="1">男
<input type="radio" name="sex" id="" value="2">女
<input type="radio" name="sex" id="" value="3" checked="checked">保密<br>
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<input type="checkbox" name="fav[]" id="" value="1" checked="checked" />PHP
<input type="checkbox" name="fav[]" id="" value="2" checked="checked" />PHP
<br>
<input type="email" placeholder="2306613258@qq.com">
年龄<input type="number" min="1" max="3" value="1">
<input type="submit" name="" value="reg">
</form>
</body>
</html>问题：怎么显示input[type=“number”]:out-of-range { border: 1px solid yellow; }呢 ?在里面填写即可，不要按
