.acortab {
  position: relative;
  margin: 2px;
/*  max-width: 600px;*/
  max-width: 100%;
}

/* [THE LABEL] */
.acortab input {
  display: none;
}
.acortab label {
  display: block;
  background: #534F4C; /*  2b4c61  2d5faf*/
  color: #fff;
/*  font-weight: bold;*/
  padding: 10px;
  cursor: pointer;
}
.acortab label::after {
  content: "\25b6";
  position: absolute;
  right: 10px;
  top: 10px;
  display: block;
  transition: all 0.4s;
}
.acortab input[type=checkbox]:checked + label::after,
.acortab input[type=radio]:checked + label::after {
  transform: rotate(90deg);
}

/* [THE CONTENTS] */
.acortab-content {
  overflow: hidden;
  background: #ddcabd;  /* #ccdef9 */
  /* CSS animation will not work with auto height */
  /* This is why we use max-height */
  transition: max-height 0.4s; 
  max-height: 0;
}
.acortab-content p {
  margin: 20px;
}
.acortab input:checked ~ .acortab-content {
  /* Set the max-height to a large number */
  /* Or 100% viewport height */
  max-height: 100vh;
}