CSS 媒体特征 width 用于确定视口（浏览器的查看区域）的宽度（水平尺寸）。
width 媒体功能还可以与 min-width 和 max-width 属性一起使用，以设置视口的最小和最大宽度。
@media (width: <length>){
//CSS styles
}以下示例演示了当屏幕宽度为 200px 时，宽度媒体功能可将背景颜色更改为粉红色 -
<html>
<head>
<style>
iframe {
display: block;
}
</style>
</head>
<body>
<label id="labelWidth" for="height">Width: 100</label>
<input id="width" name="width" type="range" min="100" max="300" step="5" value="100" />
<iframe
id="block"
srcdoc="<style> @media (width: 200px) { div { background: pink; } } </style><div>To see the effect resize your viewport's width is 200px.</div>">
</iframe>
<script>
const updateSize = (size, label) => {
block.style[size] = `${eval(size).value}px`;
label.textContent = `${size}: ${eval(size).value}`;
};
width.oninput = () => updateSize("width", labelWidth);
</script>
</body>
</html> 以下示例演示了当屏幕宽度大于或等于 200px 时，最小宽度媒体功能将背景颜色更改为红色 -
<html>
<head>
<style>
iframe {
display: block;
}
</style>
</head>
<body>
<label id="labelWidth" for="height">Width: 200</label>
<input id="width" name="width" type="range" min="100" max="300" step="5" value="200" />
<iframe
id="block"
srcdoc="<style> @media (min-width: 200px) { div { background: red; } } </style><div>To see the effect resize your viewport's width.</div>">
</iframe>
<script>
const updateSize = (size, label) => {
block.style[size] = `${eval(size).value}px`;
label.textContent = `${size}: ${eval(size).value}`;
};
width.oninput = () => updateSize("width", labelWidth);
</script>
</body>
</html> 以下示例演示了 max-width 媒体功能，当屏幕宽度小于或等于 250px 时，将背景颜色更改为粉红色 -
<html>
<head>
<style>
iframe {
display: block;
}
</style>
</head>
<body>
<label id="labelWidth" for="height">Width: 100</label>
<input id="width" name="width" type="range" min="100" max="300" step="5" value="100" />
<iframe
id="block"
srcdoc="<style> @media (max-width: 250px) { div { background: pink; } } </style><div>To see the effect resize your viewport's width.</div>">
</iframe>
<script>
const updateSize = (size, label) => {
block.style[size] = `${eval(size).value}px`;
label.textContent = `${size}: ${eval(size).value}`;
};
width.oninput = () => updateSize("width", labelWidth);
</script>
</body>
</html> 