css网页背景满屏

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Full Screen Background</title>
    <style>
        body {
            background-color: #4CAF50; /* 设置背景颜色 */
            margin: 0;
            height: 100vh; /* 设置高度为视口高度 */
            display: flex;
            justify-content: center;
            align-items: center;
        }
    </style>
</head>
<body>
    <h1>Hello World!</h1>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Full Screen Background</title>
    <style>
        body {
            background-image: url('https://example.com/image.jpg'); /* 设置背景图片 */
            background-size: cover; /* 图片覆盖整个背景 */
            background-position: center; /* 图片居中 */
            background-repeat: no-repeat; /* 不重复显示图片 */
            margin: 0;
            height: 100vh; /* 设置高度为视口高度 */
            display: flex;
            justify-content: center;
            align-items: center;
        }
    </style>
</head>
<body>
    <h1>Hello World!</h1>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Full Screen Background</title>
    <style>
        body {
            background: linear-gradient(to right, #FF9A9E, #fad0c4); /* 设置渐变背景 */
            margin: 0;
            height: 100vh; /* 设置高度为视口高度 */
            display: flex;
            justify-content: center;
            align-items: center;
        }
    </style>
</head>
<body>
    <h1>Hello World!</h1>
</body>
</html>