codepen.css

body{
  height: 100vh;
  display: flex;
  flex-flow: column;
  align-items: center;
  justify-content: center;
  padding: 12em 0;
  box-sizing: border-box;
}

.pen-intro{

}

.repoLink{
  position: absolute;
  top: 0;
  right: 0;
  width: 18%;
  max-width: 360px;
  min-width: 160px;
}

label[for='checkbox-tagify-show-input']{
  position: absolute;
  top: .85em;
  left: 2.5em;

}

#checkbox-tagify-show-input{
  position: absolute;
  top: 1em;
  left: 1em;
  transform: scale(1.4);
}

#checkbox-tagify-show-input:checked ~ input,
#checkbox-tagify-show-input:checked ~ textarea{
  display: block !important;
  position: static !important;
  transform: none !important;
  width: 100%;
  max-width: 700px;
  margin-top: 1em;
  padding: .5em;
}

#checkbox-tagify-show-input:checked ~ textarea{
    min-height: 11ch;
}