If you are looking for some modern buttons for your next landing page, these gradient buttons in pure CSS by Gianluca Pirrera might be just the thing for you. You can change the direction of the background change in the :hover state.
If you are having trouble with the pen, try the archived copy on GitHub
CSS Gradient Button Snippet
See the Pen Gradient Buttons with Background-Color Change (CSS-only) by MrPirrera (@pirrera) on CodePen.0