css/packages/primer-utilities/lib/animations.scss

// This file contains reusable animations for github.
// stylelint-disable primer/selector-no-utility
// Fade in
// A class to fade in an element on the page.
.anim-fade-in {
  animation-name: fade-in;
  animation-duration: 1s;
  animation-timing-function: ease-in-out;

  &.fast {
    animation-duration: 300ms;
  }
}

@keyframes fade-in {
  0% {
    opacity: 0;
  }

  100% {
    opacity: 1;
  }
}

/* Fade in and slide up an element */
.anim-fade-up {
  opacity: 0;
  animation-name: fade-up;
  animation-duration: 0.3s;
  animation-fill-mode: forwards;
  animation-timing-function: ease-out;
  animation-delay: 1s;
}

@keyframes fade-up {
  0% {
    opacity: 0.8;
    transform: translateY(100%);
  }

  100% {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Fade an element out and slide down */
.anim-fade-down {
  animation-name: fade-down;
  animation-duration: 0.3s;
  animation-fill-mode: forwards;
  animation-timing-function: ease-in;
}

@keyframes fade-down {
  0% {
    opacity: 1;
    transform: translateY(0);
  }

  100% {
    opacity: 0.5;
    transform: translateY(100%);
  }
}

/* Grow an element width from 0 to 100% */
.anim-grow-x {
  width: 0%;
  animation-name: grow-x;
  animation-duration: 0.3s;
  animation-fill-mode: forwards;
  animation-timing-function: ease;
  animation-delay: 0.5s;
}

@keyframes grow-x {
  to { width: 100%; }
}

/* Shrink an element from 100% to 0% */
.anim-shrink-x {
  animation-name: shrink-x;
  animation-duration: 0.3s;
  animation-fill-mode: forwards;
  animation-timing-function: ease-in-out;
  animation-delay: 0.5s;
}

@keyframes shrink-x {
  to { width: 0%; }
}

/* Fade in an element and scale it fast */
.anim-scale-in {
  animation-name: scale-in;
  animation-duration: 0.15s;
  animation-timing-function: cubic-bezier(0.2, 0, 0.13, 1.5);
}

@keyframes scale-in {
  0% {
    opacity: 0;
    transform: scale(0.5);
  }

  100% {
    opacity: 1;
    transform: scale(1);
  }
}

/* Pulse an element's opacity */
.anim-pulse {
  animation-name: pulse;
  animation-duration: 2s;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

@keyframes pulse {
  0% {
    opacity: 0.3;
  }

  10% {
    opacity: 1;
  }

  100% {
    opacity: 0.3;
  }
}

/* Pulse in an element */
.anim-pulse-in {
  animation-name: pulse-in;
  animation-duration: 0.5s;
}

@keyframes pulse-in {
  0% {
    transform: scale3d(1, 1, 1);
  }

  50% {
    transform: scale3d(1.1, 1.1, 1.1);
  }

  100% {
    transform: scale3d(1, 1, 1);
  }
}