list-inside list-decimal whitespace-normal [li_&]:pl-6

These look like custom CSS properties and a class/name used to apply a simple animation. Breakdown:

• -sd-animation: sd-fadeIn;
  • Likely a custom property specifying which named animation to use (here, “sd-fadeIn”).
• –sd-duration: 250ms;
  • Custom property for animation duration (250 milliseconds).
• –sd-easing: ease-in;
  • Custom property for animation timing function (CSS easing: ease-in).

How they might be used (example CSS):

.element {animation-name: var(–sd-animation);  animation-duration: var(–sd-duration, 250ms);  animation-timing-function: var(–sd-easing, ease-in);  animation-fill-mode: both;}
@keyframes sd-fadeIn {  from { opacity: 0; transform: translateY(6px); }  to   { opacity: 1; transform: translateY(0); }}

Notes:

• The names starting with a dash (e.g., -sd-animation) are allowed but nonstandard; standard CSS custom properties should start with two dashes (e.g., –sd-animation).
• Use var(–sd-duration) and var(–sd-easing) to make animations configurable.
• Include sensible fallbacks in var() calls.
• For accessibility, prefer reduced-motion media query:

@media (prefers-reduced-motion: reduce) {  .element { animation: none; }}