代码运行后为什么拖拽屏幕看不到效果
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<title>媒体查询</title>
<style>
#div0{
width: 100px;
height: 200px;
}
/* @media screen 屏幕尺寸*/
@media screen and (min-device-width:200px) and(max-device-width:300px) {
#div0{
background-color: yellow;
}
}
@media screen and(min-device-width:301px) and(max-device-width:500px){
#div0{
background-color: blue;
}
}
</style>
</head>
<body>
<div id="div0"></div>
</body>
</html>
