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Those are CSS custom properties (variables) plus a shorthand-like property that together control a simple animation pattern. Breakdown:

• -sd-animation: sd-fadeIn;
  • Likely a custom (project-specific) property naming convention using the ”-sd-” prefix.
  • The value “sd-fadeIn” names an animation (probably defined with @keyframes or mapped in JavaScript/CSS to apply fade-in behavior).
• –sd-duration: 250ms;
  • A CSS custom property holding the animation duration (250 milliseconds).
  • Can be referenced in animation rules as var(–sd-duration).
• –sd-easing: ease-in;
  • A CSS custom property for the timing function (easing) used by the animation.

How they might be used (example pattern):

• Define keyframes:
  @keyframes sd-fadeIn {from { opacity: 0; transform: translateY(6px); }  to   { opacity: 1; transform: translateY(0); }}

• Apply on an element using the variables:
  .my-element {  animation-name: var(-sd-animation); /* or directly sd-fadeIn */  animation-duration: var(–sd-duration);  animation-timing-function: var(–sd-easing);  animation-fill-mode: both;}

Notes and tips:

• Custom properties are strings; ensure animation-name matches exactly.
• If -sd-animation is a custom property (leading hyphen), access it with var(–sd-animation) — the example uses a single dash; consider normalizing to two dashes (e.g., –sd-animation) for consistency with CSS custom property syntax.
• Use fallback values: var(–sd-duration, 300ms).
• @media (prefers-reduced-motion: reduce) {  .my-element { animation: none; transition: none; }}