metamask-extension/ui/components/component-library/button-base/button-base.scss

.mm-button-base {
  position: relative;
  height: 40px;
  cursor: pointer;
  vertical-align: middle;
  user-select: none;
  font-weight: 600;

  &--block {
    width: 100%;
  }

  &--ellipsis {
    max-width: 100%;
  }

  &--size-sm {
    height: 32px;
  }

  &--size-md {
    height: 40px;
  }

  &--size-lg {
    height: 48px;
  }

  &--loading {
    cursor: not-allowed;
  }

  &--disabled,
  &:disabled {
    opacity: var(--opacity-disabled);
    cursor: not-allowed;
  }

  &__icon-loading {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation: spinner 1.2s linear infinite;
  }
}

a.mm-button-base:hover {
  color: var(--color-text-default);
}



@keyframes spinner {
  to { transform: translate(-50%, -50%) rotate(360deg); }
}