This is a modern minimal range slider by Marine Piette with a circle above the range indicator that shows the current number of the range as you slide it along. You can also click anywhere along the range slider to jump to that number.
If you are having trouble with the pen, try the archived copy on GitHub
Range Slider with Number Code Snippet
See the Pen Slider Range Mars Weight Calculator by Marine Piette (@mayuMPH) on CodePen.default