Pen Settings



CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URLs added here will be added as <link>s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.

+ add another resource


Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource


Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.


Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.


                - const randomInRange = (max, min) => Math.floor(Math.random() * (max - min + 1)) + min
- const baseHue = randomInRange(0, 360)
- const bubbleCount = 30
- let b = 0
while b < bubbleCount
  - const size = randomInRange(10, 50)
  - const delay = randomInRange(1, 10)
  - const speed = randomInRange(2, 20)
  - const distance = randomInRange(50, 250)
  - const scale = randomInRange(100, 150) / 100
  - const x = randomInRange(0, 100)
  .bubble(style=`--x: ${x}; --size: ${size}; --hue: ${baseHue}; --distance: ${distance}; --speed: ${speed}; --delay: ${delay}; --scale: ${scale}`)
  - b++


  align-items center
  background #111
  display flex
  justify-content center
  min-height 100vh
  overflow hidden

  --bubble-outline 'hsl(%s, 100%, 50%)' % var(--hue)
  --bubble-spot 'hsl(%s, 100%, 75%)' % var(--hue)
  --bubble-shade 'hsl(%s, 100%, 70%)' % var(--hue)
  animation-name float
  animation-duration calc(var(--speed) * 1s)
  animation-delay calc(var(--delay) * -1s)
  animation-iteration-count infinite
  animation-timing-function ease-in-out
  background radial-gradient(100% 115% at 25% 25%, #fff, transparent 33%), radial-gradient(15% 15% at 75% 75%, var(--bubble-spot), transparent), radial-gradient(100% 100% at 50% 25%, transparent, var(--bubble-shade) 98%)
  border 1px solid var(--bubble-outline)
  border-radius 100%
  height calc(var(--size) * 1px)
  left calc(var(--x) * 1%)
  position absolute
  top 100%
  transform translate(-50%, 0)
  width calc(var(--size) * 1px)
  will-change transform
@keyframes float
    opacity 1
    transform translate(-50%, 0) scale(0)
    opacity 1
    opacity 0
    transform translate(-50%, calc(var(--distance) * -1vh)) scale(var(--scale))