webkit - Glitches when using css gradient mask image with 3d transforms - Stack Overflow
Using Masks
CSS mask-image with linear gradient not working in Edge - Stack Overflow
CSS Masking - The mask-image Property
Adam Argyle on Twitter: "```#css -webkit-mask-image: linear-gradient(to right, #0000, #000, #000, #0000) ``` wrote that last night to give a horizontal scroller a nice "scroll hint" by masking it's edges; scroller edge