css - Style lower and upper fill in HTML5 range input

Question

As explained here, IE allows styling of the lower and upper fill or track regions in CSS as follows:

/* The following only affects the range input in IE */

input[type="range"]::-ms-fill-lower {
  background-color: red; 
}

input[type="range"]::-ms-fill-upper {  
  background-color: blue;
}

<input type="range">

Answer 1

First of all, read the article Styling Cross-Browser Compatible Range Inputs with CSS by Daniel Stern. His idea is to make the input invisible and then apply the custom styles.

He also developed an excellent online tool named randge.css in which you select the style preset and parameters and get auto generated CSS code like the following one:

input[type=range] {
  -webkit-appearance: none;
  margin: 10px 0;
  width: 100%;
}
input[type=range]:focus {
  outline: none;
}
input[type=range]::-webkit-slider-runnable-track {
  width: 100%;
  height: 12.8px;
  cursor: pointer;
  animate: 0.2s;
  box-shadow: 0px 0px 0px #000000, 0px 0px 0px #0d0d0d;
  background: #ac51b5;
  border-radius: 25px;
  border: 0px solid #000101;
}
input[type=range]::-webkit-slider-thumb {
  box-shadow: 0px 0px 0px #000000, 0px 0px 0px #0d0d0d;
  border: 0px solid #000000;
  height: 20px;
  width: 39px;
  border-radius: 7px;
  background: #65001c;
  cursor: pointer;
  -webkit-appearance: none;
  margin-top: -3.6px;
}
input[type=range]:focus::-webkit-slider-runnable-track {
  background: #ac51b5;
}
input[type=range]::-moz-range-track {
  width: 100%;
  height: 12.8px;
  cursor: pointer;
  animate: 0.2s;
  box-shadow: 0px 0px 0px #000000, 0px 0px 0px #0d0d0d;
  background: #ac51b5;
  border-radius: 25px;
  border: 0px solid #000101;
}
input[type=range]::-moz-range-thumb {
  box-shadow: 0px 0px 0px #000000, 0px 0px 0px #0d0d0d;
  border: 0px solid #000000;
  height: 20px;
  width: 39px;
  border-radius: 7px;
  background: #65001c;
  cursor: pointer;
}
input[type=range]::-ms-track {
  width: 100%;
  height: 12.8px;
  cursor: pointer;
  animate: 0.2s;
  background: transparent;
  border-color: transparent;
  border-width: 39px 0;
  color: transparent;
}
input[type=range]::-ms-fill-lower {
  background: #ac51b5;
  border: 0px solid #000101;
  border-radius: 50px;
  box-shadow: 0px 0px 0px #000000, 0px 0px 0px #0d0d0d;
}
input[type=range]::-ms-fill-upper {
  background: #ac51b5;
  border: 0px solid #000101;
  border-radius: 50px;
  box-shadow: 0px 0px 0px #000000, 0px 0px 0px #0d0d0d;
}
input[type=range]::-ms-thumb {
  box-shadow: 0px 0px 0px #000000, 0px 0px 0px #0d0d0d;
  border: 0px solid #000000;
  height: 20px;
  width: 39px;
  border-radius: 7px;
  background: #65001c;
  cursor: pointer;
}
input[type=range]:focus::-ms-fill-lower {
  background: #ac51b5;
}
input[type=range]:focus::-ms-fill-upper {
  background: #ac51b5;
}

body {
  padding: 30px;
}

<input type="range">