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                <div class="wrapper">
  <input id="c1" type="checkbox"><label for="c1"></label>
  <input id="c2" type="checkbox" checked><label for="c2"></label>
  <input id="c3" type="checkbox" checked><label for="c3"></label>
  <input id="c4" type="checkbox"><label for="c4"></label>
  <input id="c5" type="checkbox"><label for="c5"></label>



                input:checked {
  counter-increment: total;

output::before {
  content: counter(total);

/* checkboxes don't scale up in size very well in all browsers, so we'll hide them in an accessible way... */
input {
  position: absolute;
  width: 1px;
  clip: rect(0 0 0 0);
  overflow: hidden;
  white-space: nowrap;

/* ...and style every <label> to look like a checkbox... */
label {
  display: grid;
  place-items: center;
  width: 50px;
  height: 50px;
  background-color: #fff;
  overflow: hidden;

/* ...and add in a focus style to keep things accessible... */
input:focus + label {
  outline: 2px solid #406f99;

/* ...and add a checkmark into <label> via ::before whenever its actual (hidden) checkbox is checked */
input:checked + label::before {
  content: '✔';

/* everything below is for demo appearances and not important to the concept */

body {
  box-sizing: border-box;
  display: grid;
  place-items: center;
  min-height: 100vh;
  margin: 0;
  padding: 20px;
  color: #406f99;
  background-color: #cbd9e6;
  font: 700 2.5rem/1 'Fira Mono', monospace;

.wrapper {
  display: flex;
  justify-content: space-between;
  width: 100%;
  max-width: 500px;

span, output {
  height: 50px;
  line-height: 50px;