These look like CSS custom properties and a (prefixed) property used to control a simple animation pattern. Brief explanations:
- -sd-animation: sd-fadeIn;
- Likely a custom (prefixed) property signaling which animation to apply; “sd-fadeIn” names the animation behavior (probably defined elsewhere as keyframes or a utility).
- –sd-duration: 0ms;
- CSS custom property holding the animation duration. 0ms means the animation runs instantly (no visible transition).
- –sd-easing: ease-in;
- CSS custom property for the timing function (easing) — “ease-in” starts slow then speeds up.
How they’re typically used
- Define keyframes for the named animation (sd-fadeIn) and then reference the custom properties when setting animation shorthand or transition:
@keyframes sd-fadeIn {from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: translateY(0); }} .sd-animated { animation-name: var(–sd-animation); animation-duration: var(–sd-duration); animation-timing-function: var(–sd-easing); animation-fill-mode: both;} - With –sd-duration: 0ms, the element will jump to the final state immediately; set a positive duration (e.g., 250ms) for visible animation.
Notes and best practices
- Use meaningful defaults (e.g., 200ms–400ms durations) and expose these vars for theming/components.
- Prefer prefers-reduced-motion handling: set duration to 0ms when user requests reduced motion.
- Ensure the named animation (sd-fadeIn) exists; otherwise animation-name: var(–sd-animation) does nothing.
- Keep vendor prefixes only if supporting very old browsers.
If you want, I can:
- Provide a complete example with CSS and HTML demonstrating sd-fadeIn and prefers-reduced-motion handling.
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