nav input[type="checkbox"] { display:none; }

nav label {
  display: inline-block;
  margin-top: 12px;
  padding: 5px 11px;
  background-color: red;
  border: 1px solid;
  border-radius: 3px;
    width: 100%;
    height: 100%;
}

nav input[type="checkbox"]:checked ~ label {
  background-color: green;
}

nav input[type="checkbox"]:disabled ~ label {
  background-color: grey;
}

nav div {
    width: 50%;
    display: inline-block;
    padding: 10px;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

nav {
    display: flex;
}

body > div {
    border: 1px solid black;
    margin: 10px;
    padding: 10px;
    border-radius: 5px;
}

#stats input {
    border: 0;
}