speedtest/frontend/styling/button.css

/* The main "start the test" button and the share button */

button {
  height: 6.8rem;
  min-width: 26.4rem;
  padding: 0 5rem;
  margin: 2.5rem;
  border-radius: 3.4rem;
  border: 0;

  font-family: "Inter", sans-serif;
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.1rem;
  color: var(--button-text-color);
  text-transform: uppercase;
  cursor: pointer;
  box-shadow: 0 0.4rem 1.6rem 0 var(--button-shadow-color);

  will-change: transform;
  backface-visibility: hidden;
  transform: scale(1) translate3d(0, 0, 0) perspective(1px);

  background: var(--button-gradient-1-color-1);
  transition: background-position 0.2s, transform 0.2s;
  background-position: 0% 0%;
  background: linear-gradient(
    92.97deg,
    var(--button-gradient-1-color-1) 0%,
    var(--button-gradient-1-color-1) 33%,
    var(--button-gradient-1-color-2) 40%,
    var(--button-gradient-1-color-3) 66.71%,
    var(--button-gradient-1-color-3) 100%
  );
  background-size: 300% 100%;

  &.disabled {
    cursor: default;
    transform: scale(1) translate3d(0, 0, 0) perspective(1px);
    background: var(--button-disabled-background-color);
  }
  &.small {
    height: 4.7rem;
    min-width: 20.2rem;
    text-transform: lowercase;
  }
  &.inverted {
    border: 1px solid var(--button-gradient-1-color-1);
    color: transparent;
    background-clip: text;
  }
  &.hidden {
    opacity: 0;
    pointer-events: none;
  }
  &:hover {
    background-position: 60% 0%;
    transform: scale(1.03) translate3d(0, 0, 0) perspective(1px);
  }
  &.active,
  &:active {
    background-position: 100% 0%;
    animation: pulse 0.7s;
  }
}

@keyframes pulse {
  0% {
    transform: scale(1.03) translate3d(0, 0, 0) perspective(1px);
  }
  20% {
    transform: scale(1.2) translate3d(0, 0, 0) perspective(1px);
  }
  40% {
    transform: scale(1) translate3d(0, 0, 0) perspective(1px);
  }
  60% {
    transform: scale(1.1) translate3d(0, 0, 0) perspective(1px);
  }
  100% {
    transform: scale(1) translate3d(0, 0, 0) perspective(1px);
  }
}