countdown which save in localstorage timer, for BVB

code.html

<div class="bvb_bc_countdown bc_15_min">
  <span class="bvb_panel bvb_minute">
    <span class="tdigit">00</span>
    <span class="tlabel">minutes</span>
  </span>
  <span class="bvb_panel bvb_sec">
    <span class="tdigit">00</span>
    <span class="tlabel">seconds</span>
  </span>
</div>

<script>
  jQuery(function($){
      var old = localStorage.getItem("bc_start_timer");
      var default_time = 15*60; // 15 minutes
      var end = default_time; 
      var current_date = new Date();
      
      if(old){
          var end_time = new Date(old);
          end = default_time - (current_date - end_time)/1000;
      }else{
          localStorage.setItem("bc_start_timer",current_date);
      }
      
      
      if(end>=1)
      setInterval(function(){
          end--;
          if(end<1)
            return false;
          var mins = Math.floor(end/60);
          var secs = Math.floor(end - mins*60);
          $('.bc_15_min .bvb_minute .tdigit').html(mins);
          $('.bc_15_min .bvb_sec .tdigit').html(secs);
      },1000);
  });
</script>

style.css

.bvb_bc_countdown {
    text-align: center;
}

.bvb_bc_countdown .bvb_panel {
    display: inline-block;
    margin-right: 10px;
    min-width: 120px;
    color: #FFF;
}

.bvb_bc_countdown .tdigit {
    font-size: 30px;
    font-weight: 500;
    display: inline-block;
    width: 100%;
    padding: 7px;
    line-height: 100%;
    background-color: #F86855;
}

.bvb_bc_countdown .tlabel {
    font-size: 15px;
    width: 100%;
    display: inline-block;
    line-height: 100%;
}