title: <p:calendar>'s button icon disappeared after applying custom css
body: <p>In my application I am using <code>&lt;p:calendar showOn="button".......&gt;</code> and I apply custom css on this calendar with the help of this link: <a href="http://bluefoot.info/howtos/primefaces-calendar-highlight-dates" rel="nofollow noreferrer">Bluefoot-CustomCss-Primefaces-Calendar</a>.  After applying this custom css, all is working fine, except the calendar icon turned into <code>...</code>. But I want to show that <code>calendar</code> icon. How is it possible ? I have attached the picture for better understanding my problem . </p>
  
  <p>One more thing for my case html DOM tree looks like <code>&lt;button class="ui-datepicker-trigger" type="button"&gt;...&lt;/button&gt;</code> where by default this should be </p>
  
  <pre><code>&lt;button class="ui-datepicker-trigger ui-button ui-widget ui-state-default ui-corner-all ui-button-icon-only" type="button" role="button" aria-disabled="false"&gt;
     &lt;span class="ui-icon ui-icon-calendar"&gt;&lt;/span&gt;
     &lt;span class="ui-button-text"&gt;ui-button&lt;/span&gt;
  &lt;/button&gt;
  </code></pre>
  
  <p>I don't know how to solve this. Any suggestion is greatly appreciated. Thanks,
  !<img src="https://i.stack.imgur.com/e7Fsc.png" alt="enter image description here"> .</p>
  
  <p>EDIT:1
  I am calling this js method before each date show:</p>
  
  <pre><code>function applyCustomCssOnCalendar(isAccessable, isAdmin, publicHolidaysAsString, paidLeavesAsString, rttLeavesAsString, specialLeavesAsString, pendingLeavesAsString, pendingLabel, paidLeave) {
  $(".hasDatepicker").datepicker("option", "beforeShowDay",
          function(date) {
  
              return highlightCalendar(isAccessable, isAdmin, publicHolidaysAsString, paidLeavesAsString,
                      rttLeavesAsString, specialLeavesAsString, pendingLeavesAsString, pendingLabel, paidLeave, date);
          })
    };
  </code></pre>
  
  <p>applyCustomCssOnCalendar(isAccessable, isAdmin, publicHolidaysAsString, paidLeavesAsString, rttLeavesAsString, specialLeavesAsString, pendingLeavesAsString, pendingLabel, paidLeave) method is defined as :</p>
  
  <pre><code>function highlightCalendar(isAccessable, isAdmin, publicHolidaysAsString, paidLeavesAsString, rttLeavesAsString, specialLeavesAsString, pendingLeavesAsString, pendingLabel, paidLeave, datee) {
  var date = new Date(datee);
  date.setHours(0, 0, 0, 0);
  var d = date.getDate();
  var m = date.getMonth() + 1;
  var y = date.getFullYear();
  var day = date.getDay();
  
  var currentDate = new Date();
  currentDate.setHours(0, 0, 0, 0);
  
  console.log(publicHolidaysAsString);
  
  if (day == 6 || day == 0) {
      return [true,'ui-datepicker-unselectable',''];
  }   
  
  for ( var i = 0; i &lt; publicHolidaysAsString.length; i = i + 2) {
      if ((y + '-' + m + '-' + d) == publicHolidaysAsString[i]) {
          return [true,'highlight-calendar-publicHoliday ui-datepicker-unselectable',publicHolidaysAsString[i + 1]];
      }
  }
  }
  </code></pre>