W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<style>
#grad1 {
  height: 100px;
  background-color: red; /* For browsers that do not support gradients */
  background-image: linear-gradient(0deg, red, yellow);
}

#grad2 {
  height: 100px;
  background-color: red; /* For browsers that do not support gradients */
  background-image: linear-gradient(90deg, red, yellow);
}

#grad3 {
  height: 100px;
  background-color: red; /* For browsers that do not support gradients */
  background-image: linear-gradient(180deg, red, yellow);
}

#grad4 {
  height: 100px;
  background-color: red; /* For browsers that do not support gradients */
  background-image: linear-gradient(-90deg, red, yellow);
}
</style>
</head>
<body>

<h1>Linear Gradients - Using Different Angles</h1>

</body>
</html>