The reason for the darkness is that the CSS keyword transparent is actually an alias for rgba(0, 0, 0, 0) — that is, fully transparent black. A simple definition like linear-gradient(red, transparent) ...

This demonstrates the power of CSS. Here, a multi-coloured gradient animates in an infinate loop and blurs when hovered over. No libraries or JavaScript used in this demo ...

How to Use Gradient to Transparency with Adobe InDesign. Adding a gradient to an image that starts by showing an opaque image and gradually merging the image to become transparent creates an ...