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CSS

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HTML 

              
                - const COUNT = 360 / 6
mixin button(className)
  button.button(class=className)
    span.button__text Love
    span.button__icon
      span.heart__particles
        - let p = 0
        while p < COUNT
          span.heart__particle
          - p++
      svg.heart.heart--stroke(viewBox="0 0 24 24")
        path(d="M12,21.35L10.55,20.03C5.4,15.36 2,12.27 2,8.5C2,5.41 4.42,3 7.5,3C9.24,3 10.91,3.81 12,5.08C13.09,3.81 14.76,3 16.5,3C19.58,3 22,5.41 22,8.5C22,12.27 18.6,15.36 13.45,20.03L12,21.35Z")
      svg.heart.heart--fill(viewBox="0 0 24 24")
        path(d="M12,21.35L10.55,20.03C5.4,15.36 2,12.27 2,8.5C2,5.41 4.42,3 7.5,3C9.24,3 10.91,3.81 12,5.08C13.09,3.81 14.76,3 16.5,3C19.58,3 22,5.41 22,8.5C22,12.27 18.6,15.36 13.45,20.03L12,21.35Z")

+button('button--primary')
+button('button--secondary')
!

CSS 

              
                *
  box-sizing border-box

body
  min-height 100vh
  display flex
  align-items center
  justify-content center
  background hsl(0, 0%, 98%)

  & > * + *
    margin-right 24px

:root
  --transition 0.3
  --heart-fill hsl(10, 80%, 50%)

.heart
  height 100%
  width 100%
  position absolute

  &--stroke
    stroke var(--heart-stroke)
    stroke-width 2.5px
    fill none

  &--fill
    stroke none
    fill var(--heart-fill)
    transform scale(var(--scale, 0))

  &__particle
    height 16px
    width 16px
    position absolute
    top 50%
    left 50%
    border-radius 50%
    background 'hsl(%s, 80%, 70%)' % var(--h)
    transform translate(-50%, -50%) rotate(calc(var(--r, 0) * 1deg)) translate(0, calc(var(--radius, 0) * 1px)) scale(0)


.button
  height 40px
  border 0
  cursor pointer
  border-radius 6px
  position relative
  display flex
  align-items center
  justify-content center
  width 100px
  font-family sans-serif
  text-align left
  outline transparent
  color var(--stroke)
  background var(--fill)
  background 'hsl(%s, %s, %s)' % (var(--hue) calc(var(--saturation) * 1%) calc(var(--lightness) * 1%))
  box-shadow 2px 4px 4px hsla(0, 0%, 10%, 0.5)
  transition box-shadow 0.2s, background 0.2s

  &--primary
    --hue 260
    --saturation 50
    --lightness 20
    --stroke hsl(0, 0%, 100%)
    --heart-stroke hsl(0, 0%, 100%)
    margin-right 24px

  &--secondary
    --hue 0
    --saturation 0
    --lightness 100
    --stroke hsl(0, 0%, 40%)
    --heart-stroke hsl(0, 0%, 60%)


  &__text
    margin-right 6px
    opacity var(--opacity)

  &__icon
    position relative
    height 24px
    width 24px

  &:hover
    --scale 0.3
    background 'hsl(%s, %s, %s)' % (var(--hue) calc(var(--saturation) * 1%) calc(var(--lightness) * 0.96%))
    box-shadow 2px 2px 4px hsla(0, 0%, 10%, 0.5)
    .heart--fill
      transition transform calc(var(--transition) * 1s) cubic-bezier(.7,.9,.6,2.5)

  &:active
    background 'hsl(%s, %s, %s)' % (var(--hue) calc(var(--saturation) * 1%) calc(var(--lightness) * 0.92%))
    box-shadow 0 0 0 hsla(0, 0%, 10%, 0.5)

  &--active
  &--active:hover
    --scale 0.94
    --opacity 0.25


    .heart--fill
      transition transform calc(var(--transition) * 1s) cubic-bezier(.7,.9,.6,2.5)

    .button__text
      transition opacity 0.1s

    .heart__particle
      opacity 0
      transform translate(-50%, -50%) rotate(calc(var(--r, 0) * 1deg)) translate(0, calc(var(--d, 0) * 1px)) scale(var(--s))
      transition transform calc(var(--t) * 1.25s) calc(var(--transition) * 0.5s), opacity calc(var(--transition) * 0.25s) calc(var(--t) * 1.25s)
!

JS 

              
                const random = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;
const COUNT = 360 / 6;
const BTN = document.querySelectorAll(".button");

const setParticles = b => {
  const PARTICLES = b.querySelectorAll('.heart__particle')
  PARTICLES.forEach((particle, index) => {
    const CHARACTER = {
      "--d": random(30, 60),
      "--r": (360 / 25) * index,
      "--h": random(0, 360),
      "--t": random(25, 50) / 100,
      "--s": random(20, 60) / 100
    };
    particle.setAttribute(
      "style",
      JSON.stringify(CHARACTER)
        .replace(/,/g, ";")
        .substring(1, JSON.stringify(CHARACTER).length - 1)
        .replace(/"/g, "")
    );        
  })
}


BTN.forEach((b) => {
  setParticles(b)
  b.addEventListener("click", () => {
    b.classList.toggle('button--active')
    if (b.classList.contains('button--active')) setParticles(b)
  })
});
!
999px

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