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

Question

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"/>

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>

Yes, it is possible. Though I wouldn't recommend it because input range is not really supported properly by all browsers because is an new element added in HTML5 and HTML5 is only a draft (and will be for long) so going as far as to styling it is perhaps not the best choice.

Also, you'll need a bit of JavaScript too. I took the liberty of using jQuery library for this, for simplicity purposes.

Here you go: http://jsfiddle.net/JnrvG/1/.

Building on top of @dargue3's answer, if you want the thumb to be larger than the track, you want to fully take advantage of the <input type="range" /> element and go cross browser, you need a little extra lines of JS & CSS.

On Chrome/Mozilla you can use the linear-gradient technique, but you need to adjust the ratio based on the min, max, value attributes as mentioned here by @Attila O.. You need to make sure you are not applying this on Edge, otherwise the thumb is not displayed. @Geoffrey Lalloué explains this in more detail here.

Another thing worth mentioning, is that you need to adjust the rangeEl.style.height = "20px"; on IE/Older. Simply put this is because in this case "the height is not applied to the track but rather the whole input including the thumb". fiddle

/**
 * Sniffs for Older Edge or IE,
 * more info here:
 * https://stackoverflow.com/q/31721250/3528132
 */
function isOlderEdgeOrIE() {
  return (
    window.navigator.userAgent.indexOf("MSIE ") > -1 ||
    !!navigator.userAgent.match(/Trident.*rv\:11\./) ||
    window.navigator.userAgent.indexOf("Edge") > -1
  );
}

function valueTotalRatio(value, min, max) {
  return ((value - min) / (max - min)).toFixed(2);
}

function getLinearGradientCSS(ratio, leftColor, rightColor) {
  return [
    '-webkit-gradient(',
    'linear, ',
    'left top, ',
    'right top, ',
    'color-stop(' + ratio + ', ' + leftColor + '), ',
    'color-stop(' + ratio + ', ' + rightColor + ')',
    ')'
  ].join('');
}

function updateRangeEl(rangeEl) {
  var ratio = valueTotalRatio(rangeEl.value, rangeEl.min, rangeEl.max);

  rangeEl.style.backgroundImage = getLinearGradientCSS(ratio, '#919e4b', '#c5c5c5');
}

function initRangeEl() {
  var rangeEl = document.querySelector('input[type=range]');
  var textEl = document.querySelector('input[type=text]');

  /**
   * IE/Older Edge FIX
   * On IE/Older Edge the height of the <input type="range" />
   * is the whole element as oposed to Chrome/Moz
   * where the height is applied to the track.
   *
   */
  if (isOlderEdgeOrIE()) {
    rangeEl.style.height = "20px";
    // IE 11/10 fires change instead of input
    // https://stackoverflow.com/a/50887531/3528132
    rangeEl.addEventListener("change", function(e) {
      textEl.value = e.target.value;
    });
    rangeEl.addEventListener("input", function(e) {
      textEl.value = e.target.value;
    });
  } else {
    updateRangeEl(rangeEl);
    rangeEl.addEventListener("input", function(e) {
      updateRangeEl(e.target);
      textEl.value = e.target.value;
    });
  }
}

initRangeEl();

input[type="range"] {
  -webkit-appearance: none;
  -moz-appearance: none;
  width: 300px;
  height: 5px;
  padding: 0;
  border-radius: 2px;
  outline: none;
  cursor: pointer;
}


/*Chrome thumb*/

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  -moz-appearance: none;
  -webkit-border-radius: 5px;
  /*16x16px adjusted to be same as 14x14px on moz*/
  height: 16px;
  width: 16px;
  border-radius: 5px;
  background: #e7e7e7;
  border: 1px solid #c5c5c5;
}


/*Mozilla thumb*/

input[type="range"]::-moz-range-thumb {
  -webkit-appearance: none;
  -moz-appearance: none;
  -moz-border-radius: 5px;
  height: 14px;
  width: 14px;
  border-radius: 5px;
  background: #e7e7e7;
  border: 1px solid #c5c5c5;
}


/*IE & Edge input*/

input[type=range]::-ms-track {
  width: 300px;
  height: 6px;
  /*remove bg colour from the track, we'll use ms-fill-lower and ms-fill-upper instead */
  background: transparent;
  /*leave room for the larger thumb to overflow with a transparent border */
  border-color: transparent;
  border-width: 2px 0;
  /*remove default tick marks*/
  color: transparent;
}


/*IE & Edge thumb*/

input[type=range]::-ms-thumb {
  height: 14px;
  width: 14px;
  border-radius: 5px;
  background: #e7e7e7;
  border: 1px solid #c5c5c5;
}


/*IE & Edge left side*/

input[type=range]::-ms-fill-lower {
  background: #919e4b;
  border-radius: 2px;
}


/*IE & Edge right side*/

input[type=range]::-ms-fill-upper {
  background: #c5c5c5;
  border-radius: 2px;
}


/*IE disable tooltip*/

input[type=range]::-ms-tooltip {
  display: none;
}

input[type="text"] {
  border: none;
}

<input type="range" value="80" min="10" max="100" step="1" />
<input type="text" value="80" size="3" />

If you use first answer, there is a problem with thumb. In chrome if you want the thumb to be larger than the track, then the box shadow overlaps the track with the height of the thumb.

Just sumup all these answers and wrote normally working slider with larger slider thumb: jsfiddle

const slider = document.getElementById("myinput")
const min = slider.min
const max = slider.max
const value = slider.value

slider.style.background = `linear-gradient(to right, red 0%, red ${(value-min)/(max-min)*100}%, #DEE2E6 ${(value-min)/(max-min)*100}%, #DEE2E6 100%)`

slider.oninput = function() {
  this.style.background = `linear-gradient(to right, red 0%, red ${(this.value-this.min)/(this.max-this.min)*100}%, #DEE2E6 ${(this.value-this.min)/(this.max-this.min)*100}%, #DEE2E6 100%)`
};

#myinput {
  border-radius: 8px;
  height: 4px;
  width: 150px;
  outline: none;
  -webkit-appearance: none;
}

input[type='range']::-webkit-slider-thumb {
  width: 6px;
  -webkit-appearance: none;
  height: 12px;
  background: black;
  border-radius: 2px;
}

<div class="chrome">
  <input id="myinput" type="range" min="0" value="25" max="200" />
</div>