<form>
  <input class="ch" type="checkbox" name="temperature" value="is_hot">
</form>

*, *:before, *:after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
:root {
  font-size: calc(16px + (24 - 16) * (100vw - 320px)/(1600 - 320));
}
body {
  background: rgb(235,167,49);
  line-height: 1.5;
}
input {
  display: inline-block;
}
form {
  padding: 3em 1.5em 0 1.5em;
  text-align: center; 
}
.ch, .ch:before, .ch:after {
  transition: all 0.3s ease-in-out;
}
.ch {
  background-color: rgb(27,123,145);
  border-radius: 0.2em;
  box-shadow: 0 0.05em 0 0.05em rgba(0,0,0,0.3) inset;
  font-size: 4em;
  overflow: hidden;
  position: relative;
  width: 3em;
  height: 1.5em;
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  z-index: 0;
}
.ch:before, .ch:after {
  content: "";
  display: block;
  position: absolute;
}
.ch:before {
  background-color: currentColor;
  border-radius: 0.125em;
  box-shadow:
    0 0 0 0.05em inset,
    -0.12em -0.12em 0 rgb(109,148,184) inset,
    -0.4em -0.3em 0 0.05em inset,
    0.12em 0.12em 0 rgb(255,255,255) inset;
  color: rgb(149,188,224);
  opacity: 0.9;
  bottom: 0;
  left: 0.125em;
  width: 1.25em;
  height: 1.25em;
  z-index: 2;
}
.ch:after {
  background-image:
    /* white */
    radial-gradient(0.2em 0.5em at 38% 95%, rgb(255,255,255) 49%, rgba(255,255,255,0) 50%),
    radial-gradient(0.3em 0.8em at 52% 95%, rgb(255,255,255) 49%, rgba(255,255,255,0) 50%),
    radial-gradient(0.25em 0.4em at 67% 95%, rgb(255,255,255) 49%, rgba(255,255,255,0) 50%),
    /* yellow */
    radial-gradient(0.25em 0.7em at 36% 95%, rgb(255,224,0) 49%, rgba(255,224,0,0) 50%),
    radial-gradient(0.4em 1.2em at 52% 95%, rgb(255,224,0) 49%, rgba(255,224,0,0) 50%),
    radial-gradient(0.25em 0.6em at 70% 93%, rgb(255,224,0) 49%, rgba(255,224,0,0) 50%),
    /* orange */
    radial-gradient(0.3em 0.8em at 32% 81%, rgb(255,144,0) 49%, rgba(255,144,0,0) 50%),
    radial-gradient(0.5em 1.6em at 52% 95%, rgb(255,144,0) 49%, rgba(255,144,0,0) 50%),
    radial-gradient(0.3em 0.9em at 74% 86%, rgb(255,144,0) 49%, rgba(255,144,0,0) 50%),
    /* red-orange */
    radial-gradient(0.4em 1em at 25% 70%, rgb(255,76,0) 49%, rgba(255,76,0,0) 50%),
    radial-gradient(0.7em 2.75em at 52% 100%, rgb(255,76,0) 49%, rgba(255,76,0,0) 50%),
    radial-gradient(0.4em 1.2em at 79% 75%, rgb(255,76,0) 49%, rgba(255,76,0,0) 50%);

  background-position: 100% 1.5em;
  background-size: 1.5em 1.5em;
  background-repeat: no-repeat;
  border-radius: 0 0 0 0.1em / 0 0 0 0;
  box-shadow: 0 0 0 0 rgb(169,208,244) inset;
  bottom: 0;
  left: 0;
  width: 1.5em;
  height: 1.5em;
  z-index: 1;
}
/* Checked */
.ch:checked {
  background-color: rgb(92,8,8);
}
.ch:checked:before {
  border-radius: 50%;
  transform: translate(1.5em,1.5em) rotate(45deg) scale(0.5);
}
.ch:checked:after {
  background-position: 100% 0;
  box-shadow: 0 -0.15em 0 0 rgb(169,208,244) inset;
  width: 3em;
}

/* Other States */
.ch:focus {
  /* Usually an anti-A11Y practice but set to remove an annoyance just for this demo */
  outline: 0;
}