使用linear-gradient()在线性渐变上添加角度。您可以尝试运行以下代码来实现它，以将角度设置为0、90和-90度
<!DOCTYPE html>
<html>
<head>
<style>
#demo1 {
height: 100px;
background: linear-gradient(0deg, orange, blue);
}
#demo2 {
height: 100px;
background: linear-gradient(90deg, orange, blue);
}
#demo3 {
height: 100px;
background: linear-gradient(-90deg, orange, blue);
}
</style>
</head>
<body>
<h2>Linear Gradients</h2>
<div id = "demo1">0 degree</div><br>
<div id = "demo2">90 degrees</div><br>
<div id = "demo3">-90 degrees</div>
</body>
</html>