Corners, exactly how you want them
Rounded corners are simple until you want them uneven — a card with two rounded top corners and square bottom ones, say. This generator gives each corner its own slider and shows the result live, so you can shape a box precisely instead of guessing at four numbers.
The right shorthand
The output uses the standard clockwise shorthand, so it drops straight into your stylesheet. Keep the corners linked for a uniform radius, or unlink them for asymmetric shapes. It all runs on your device with nothing to upload.