:root{
  /* Restrained: colour and opacity transitions only. No bounces, no reveal-on-scroll. */
  --ease-standard:cubic-bezier(.2,.6,.3,1); /* @kind other */
  --dur-fast:120ms; /* @kind other */
  --dur-base:180ms; /* @kind other */
  --dur-slow:280ms; /* @kind other */
  --transition-interactive:background-color var(--dur-base) var(--ease-standard),
    border-color var(--dur-base) var(--ease-standard),
    color var(--dur-base) var(--ease-standard),
    opacity var(--dur-base) var(--ease-standard);
}