Edit in JSFiddle

const setCalender = ($target) => {

  let $calender = $('.calender', $target);
  $($calender[0]).datepicker({
    showOtherMonths: true,
    onClose: function(dateText, inst) {
      $($calender[1]).datepicker('option', 'minDate', dateText);
      $($calender[0]).val(dateText);
    }
  });

  $($calender[1]).datepicker({
    showOtherMonths: true,
    onClose: function(dateText, inst) {
      $($calender[0]).datepicker('option', 'maxDate', dateText);
      $($calender[1]).val(dateText);
    }
  });
  
};
setCalender($('#js-calender'));


const inlineCalender = ($target) => {

	$('#js-inline-calender').datepicker({
    onSelect: function(dateText, inst) {
      $target.val(dateText);
    }
  });

};
inlineCalender($('#js-output'));

<h1 class="h1">simple calender</h1>
<div class="wrap">
  <div class="inner">
    <section class="section" id="js-calender">
      <p>FROM:<br><input type="text" class="calender"></p>
      <p>TO:<br><input type="text" class="calender"></p>
    </section>
    <section class="section">
      <div id="js-inline-calender"></div>
      <input type="text" class="calender" id="js-output">
    </section>
  </div>
</div>
<link href="https://fonts.googleapis.com/css?family=Dancing+Script:400,700" rel="stylesheet">

body {
	width: 100%;
  min-height: 100vh;
  background-image: linear-gradient(60deg, #F7CAC9 15%, #91A8D0 85%);
}

.h1 {
  margin: 1.2em;
  font-family: 'Dancing Script', cursive;
  color: rgba(white, .85);
}

.wrap {
  display: flex;
  justify-content: center;
  align-items: center;
}

.inner {
  padding-right: 1em;
  padding-left: 1em;
	min-width: 300px;
}

.section {
  max-width: 480px;
  padding: 1em;
  border: 6px double currentColor;
  //
  + .section {
    margin-top: 2rem;
  }
}

.calender {
  display: inline-block;
  height: 50px;
  width: 400px;
  padding-left: 1em;
  //
  + .calender {
    margin-top: 1rem;
  }
}

//
//////
$primary-color: #ccc;
$white: #fafafa;

.ui-datepicker {
  width: 420px;
  text-align: center;
  background: $white;
  margin: 0 0 10px 0;
  border: 2px solid $primary-color;
  box-shadow: 0 0 120px rgba(black, .2);
}

.ui-datepicker a {
  color: $primary-color;
}

.ui-datepicker-calendar {
  width: 100%;
}

.ui-datepicker-group {
  margin: 0 0 10px 0;
  background: $primary-color;
}

.ui-datepicker-header {
  color: $primary-color;
  padding: 15px;
  text-transform: uppercase;
  letter-spacing: 3px;
}

.ui-datepicker-calendar thead th {
  color: $primary-color;
  padding: 10px;
  border-top: 2px solid rgba($primary-color,1);
}

.ui-datepicker-calendar th,
.ui-datepicker-calendar td {
  font-size: 14px;
  color: $primary-color;
  text-align: center;
  border: 1px solid rgba($primary-color,.5);
}

.ui-datepicker-calendar td span {
  display: block;
  padding: 10px;
}

.ui-datepicker-calendar td a {
  color: $primary-color;
  display: block;
  padding: 10px;
  //
  &:hover {
    color: $white;
    background-color: $primary-color;
  }
  //
  &.ui-state-active {
    color: $white;
    background: $primary-color;
  }
}

.ui-datepicker-title {
  clear: both;
}

.ui-datepicker-prev {
  float: left;
}

.ui-datepicker-next {
  float: right;
}