A tutorial about jQuery UI datepicker implementation styled as a Google Material Designed widget.

<input type="text" data-type="date" id="date-input" />
<div id="material-header-holder" style="display:none">
  <div class="ui-datepicker-material-header">
    <div class="ui-datepicker-material-day">
    </div>
    <div class="ui-datepicker-material-date">
      <div class="ui-datepicker-material-month">
      </div>
      <div class="ui-datepicker-material-day-num">
      </div>
      <div class="ui-datepicker-material-year">
      </div>
    </div>
  </div>
</div>

@import "bourbon";

@import url(http://fonts.googleapis.com/css?family=Roboto:400,700);

$main-color: #284B72;
$width: 325px;

.ui-datepicker,
.ui-datepicker-material-header {
  font-family: 'Roboto';  
}

.ui-datepicker-material-header {
  display: block;
  background-color: $main-color;
  color: white;
  text-align: center;
  width: $width;
  
  .ui-datepicker-material-day {
    background-color: #1F3A58;
    padding: 10px;
    font-size: 1rem;
  }
  
  .ui-datepicker-material-date {
    padding: 20px;
    
    .ui-datepicker-material-month,
    .ui-datepicker-material-day-num,
    .ui-datepicker-material-year {
      padding: 5px;
    }
    .ui-datepicker-material-month {
      font-size: 2rem;
      text-transform: uppercase;
    }
    
    .ui-datepicker-material-day-num {
      font-size: 4.5rem;
    }
    
    .ui-datepicker-material-year {
      font-size: 1.8rem;
      font-weight: 200;
      color: rgba(255, 255, 255, 0.4);
    }
  }
}

.ui-datepicker {
  padding: 0;
  border: none;
  box-shadow: 0 12px 36px 16px rgba(0,0,0,0.24);
  width: $width;
}

.ui-corner-all {
  border-radius: 0;
}

.ui-widget-header {
  border: 0;
}

.ui-datepicker-header {
  text-align: center;
  background: white;
  padding-bottom: 15px;
  font-weight: 300;
  
  .ui-datepicker-prev,
  .ui-datepicker-next,
  .ui-datepicker-title {
    border: none;
    outline: none;
    margin: 5px;
  }
}

.ui-datepicker-prev.ui-state-hover,
.ui-datepicker-next.ui-state-hover {
  border: none;
  outline: none;
  background: lighten($main-color, 50%);
}

.ui-datepicker-calendar {
  .ui-state-default {
    background: none;
    border: none;
    text-align: center;
    height: 33px;
    width: 33px;
    line-height: 36px;
  }
  
  .ui-state-highlight {
    color: $main-color;
  }
  
  .ui-state-active {
    border-radius: 50%;
    background-color: $main-color;
    color: white;
  }
  
  thead th {
    color: #999999;
    font-weight: 200;
  }
}

.ui-datepicker-buttonpane {
  border: none;
  
  .ui-state-default {
    background: white;
    border: none;
  }

  .ui-datepicker-close,
  .ui-datepicker-current {
    background: white;
    color: $main-color;
    text-transform: uppercase;
    border: none;
    opacity: 1;
    font-weight:200;
    outline: none;
    
    &:hover {
      background: lighten($main-color, 50%);
    }
  }
}

var headerHtml = $("#material-header-holder .ui-datepicker-material-header");

var changeMaterialHeader = function(header, date) {
  var year   = date.format('YYYY');
  var month  = date.format('MMM');
  var dayNum = date.format('D');
  var isoDay = date.isoWeekday();
  
	var weekday = new Array(7);
	weekday[1] = "Monday";
	weekday[2] = "Tuesday";
	weekday[3] = "Wednesday";
	weekday[4] = "Thursday";
	weekday[5] = "Friday";
	weekday[6] = "Saturday";
	weekday[7]=  "Sunday";

  $('.ui-datepicker-material-day', header).text(weekday[isoDay]);
  $('.ui-datepicker-material-year', header).text(year);
  $('.ui-datepicker-material-month', header).text(month);
  $('.ui-datepicker-material-day-num', header).text(dayNum);
};

$.datepicker._selectDateOverload = $.datepicker._selectDate;
$.datepicker._selectDate = function(id, dateStr) {
  var target = $(id);
  var inst = this._getInst(target[0]);
  inst.inline = true;
  $.datepicker._selectDateOverload(id, dateStr);
  inst.inline = false;
  this._updateDatepicker(inst);
  
  headerHtml.remove();
  $(".ui-datepicker").prepend(headerHtml);
};

$("input[data-type='date']").on("focus", function() {
 	$(".ui-datepicker").prepend(headerHtml);
});

$("input[data-type='date']").datepicker({
  showButtonPanel: true,
  closeText: 'OK',
  onSelect: function(date, inst) {
    changeMaterialHeader(headerHtml,moment(date, 'MM/DD/YYYY'));
  },
});

changeMaterialHeader(headerHtml, moment());
$('input').datepicker('show');