HTML

CSS

JS

.slider {
  --slider-width: 100%;
  --slider-height: 50px;
  --slider-bg: rgb(82, 82, 82);
  --slider-border-radius: 9px;
  --level-color: #fff;
  --level-transition-duration: 0.1s;
  --icon-margin: 15px;
  --icon-color: var(--slider-bg);
  --icon-size: 25px;
}

.slider {
  position: relative;
  cursor: pointer;
  display: -webkit-inline-box;
  display: -ms-inline-flexbox;
  display: inline-flex;
  -webkit-box-orient: horizontal;
  -webkit-box-direction: reverse;
  -ms-flex-direction: row-reverse;
  flex-direction: row-reverse;
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center;
}

.slider .volume {
  display: inline-block;
  vertical-align: top;
  margin-right: var(--icon-margin);
  color: var(--icon-color);
  width: var(--icon-size);
  height: auto;
  position: absolute;
  left: 0;
  pointer-events: none;
}

.slider .level {
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  width: var(--slider-width);
  height: var(--slider-height);
  background: var(--slider-bg);
  overflow: hidden;
  border-radius: var(--slider-border-radius);
  -webkit-transition: height var(--level-transition-duration);
  -o-transition: height var(--level-transition-duration);
  transition: height var(--level-transition-duration);
  cursor: inherit;
  transform: rotate(270deg);
}

.slider .level::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 0;
  height: 0;
  -webkit-box-shadow: -200px 0 0 200px var(--level-color);
  box-shadow: -200px 0 0 200px var(--level-color);
}

.slider .level::-moz-range-thumb {
  width: 0;
  height: 0;
  border-radius: 0;
  border: none;
  box-shadow: -200px 0 0 200px var(--level-color);
}

Volume Slider

Very simple and modern design of a slider input for volume adjustment. The volume is a SVG icon and you can easily change it to anything you want by changing lines 3 to 28.