In the Applied Visual Design: Create a Gradual CSS Linear Gradient challenge, the explanation for the linear-gradient function describes an input of 90deg results in a vertical gradient. When I tried that input the first color started on the left side of the element and the second color ended on the right side of the element. Maybe the naming convention is counter-intuitive, but wouldn’t this be a horizontal gradient. The example for the 45deg input also seems to be mirrored across the y-axis if the gradient line is considered to be a vector in the direction from the first color to the last color. Since I can’t post links yet, you can search for linear-gradient() CSS: Cascading Style Sheets|MDN to find Mozilla’s explanation of the topic with a visual of the gradient line under the ‘Composition of a Linear Gradient’ section. I believe the example visual could be achieved with 135deg input. Maybe the vertical statement for 90deg input is referring to the direction of the lines drawn to create the gradient which are perpendicular to the gradient line. Maybe just a mute point since it doesn’t cause problems as long as you are consistent with the naming structure.