How to style HTML5 range input to have different color before and after slider?

While the accepted answer is good in theory, it ignores the fact that the thumb then cannot be bigger than size of the track without being chopped off by the overflow: hidden. See this example of how to handle this with just a tiny bit of JS.

// .chrome styling Vanilla JS

document.getElementById("myinput").oninput = function() {
  var value = (this.value-this.min)/(this.max-this.min)*100
  this.style.background = 'linear-gradient(to right, #82CFD0 0%, #82CFD0 ' + value + '%, #fff ' + value + '%, white 100%)'
};
#myinput {
  background: linear-gradient(to right, #82CFD0 0%, #82CFD0 50%, #fff 50%, #fff 100%);
  border: solid 1px #82CFD0;
  border-radius: 8px;
  height: 7px;
  width: 356px;
  outline: none;
  transition: background 450ms ease-in;
  -webkit-appearance: none;
}
<div class="chrome">
  <input id="myinput" min="0" max="60" type="range" value="30" />
</div>

Pure CSS solution:

  • Chrome: Hide the overflow from input[range], and fill all the space left to thumb with shadow color.
  • IE: no need to reinvent the wheel: ::-ms-fill-lower
  • Firefox no need to reinvent the wheel: ::-moz-range-progress

/*Chrome*/
@media screen and (-webkit-min-device-pixel-ratio:0) {
    input[type='range'] {
      overflow: hidden;
      width: 80px;
      -webkit-appearance: none;
      background-color: #9a905d;
    }
    
    input[type='range']::-webkit-slider-runnable-track {
      height: 10px;
      -webkit-appearance: none;
      color: #13bba4;
      margin-top: -1px;
    }
    
    input[type='range']::-webkit-slider-thumb {
      width: 10px;
      -webkit-appearance: none;
      height: 10px;
      cursor: ew-resize;
      background: #434343;
      box-shadow: -80px 0 0 80px #43e5f7;
    }

}
/** FF*/
input[type="range"]::-moz-range-progress {
  background-color: #43e5f7; 
}
input[type="range"]::-moz-range-track {  
  background-color: #9a905d;
}
/* IE*/
input[type="range"]::-ms-fill-lower {
  background-color: #43e5f7; 
}
input[type="range"]::-ms-fill-upper {  
  background-color: #9a905d;
}
<input type="range"/>