popup.css

body {
  width: 20rem;
}

ul {
  list-style-type: none;
  padding-inline-start: 0;
  margin: 1rem 0;
}

li {
  padding: 0.25rem;
}
li:nth-child(odd) {
  background: #80808030;
}
li:nth-child(even) {
  background: #ffffff;
}

h3,
p {
  margin: 0;
}

/* The switch - the box around the slider */
.switch {
  position: relative;
  display: inline-block;
  width: 30px;
  height: 15px;
}

/* Hide default HTML checkbox */
.switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

/* The slider */
.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: #ccc;
  -webkit-transition: .4s;
  transition: .4s;
}

.slider:before {
  position: absolute;
  content: "";
  height: 10px;
  width: 10px;
  left: 2px;
  bottom: 2.5px;
  background-color: white;
  -webkit-transition: .4s;
  transition: .4s;
}

input:checked + .slider {
  background-color: #2196F3;
}

input:focus + .slider {
  box-shadow: 0 0 1px #2196F3;
}

input:checked + .slider:before {
  -webkit-transform: translateX(16px);
  -ms-transform: translateX(16px);
  transform: translateX(16px);
}

/* Rounded sliders */
.slider.round {
  border-radius: 15px;
}

.slider.round:before {
  border-radius: 50%;
}