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These look like custom CSS properties (CSS variables) used to control an animation. Breakdown:

• -sd-animation: sd-fadeIn;
  • Likely a custom property naming convention (prefix -sd-). The value “sd-fadeIn” probably references a named animation defined elsewhere (e.g., a keyframes rule or a CSS class that applies keyframes).
• –sd-duration: 0ms;
  • Animation duration. 0ms means the animation completes instantly (no visible transition).
• –sd-easing: ease-in;
  • Timing function controlling acceleration. “ease-in” starts slow and speeds up.

How they work together

• A component or stylesheet likely reads these variables to apply an animation, e.g.:
  animation-name: var(-sd-animation);animation-duration: var(–sd-duration);animation-timing-function: var(–sd-easing);

• With duration 0ms the animation will not animate visually; it will jump immediately to the final state. If you want a visible fade-in, set –sd-duration to a positive value (e.g., 300ms) and ensure sd-fadeIn is defined, for example:
  @keyframes sd-fadeIn {from { opacity: 0; transform: translateY(8px); }  to   { opacity: 1; transform: translateY(0); }}

Notes and tips

• Confirm where “sd-fadeIn” is defined (keyframes or utility class).
• Use consistent variable names (custom properties must start with – to be standard; -sd-animation is nonstandard but valid as a custom property name).
• For accessibility, avoid instant animations for content users need to perceive; prefer reduced-motion support:
  @media (prefers-reduced-motion: reduce) {  :root { –sd-duration: 0ms; }}

If you want, I can convert these into a complete example component or show how to change them for a smooth fade-in.