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/* .modal-fullscreen */
.modal-fullscreen {
  background: transparent;
}
.modal-fullscreen .modal-content {
  background: transparent;
  border: 0;
  -webkit-box-shadow: none;
  box-shadow: none;
}
.modal-backdrop.modal-backdrop-fullscreen {
  background: #ffffff;
}
.modal-backdrop.modal-backdrop-fullscreen.in {
  opacity: .97;
  filter: alpha(opacity=97);
}
/* .modal-fullscreen size: we use Bootstrap media query breakpoints */
.modal-fullscreen .modal-dialog {
  margin: 0;
  margin-right: auto;
  margin-left: auto;
  width: 100%;
}
@media (min-width: 768px) {
  .modal-fullscreen .modal-dialog {
    width: 750px;
  }
}
@media (min-width: 992px) {
  .modal-fullscreen .modal-dialog {
    width: 970px;
  }
}
@media (min-width: 1200px) {
  .modal-fullscreen .modal-dialog {
     width: 1170px;
  }
}

<!-- Button modal fullscreen -->
<button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#modal-fullscreen">
  Launch modal fullscreen
</button>

<!-- Modal fullscreen -->
<div class="modal modal-fullscreen fade" id="modal-fullscreen" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span></button>
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
      </div>
    </div>
  </div>
</div>

// .modal-backdrop classes
$(".modal-fullscreen").on('show.bs.modal', function () {
  setTimeout( function() {
    $(".modal-backdrop").addClass("modal-backdrop-fullscreen");
  }, 0);
});
$(".modal-fullscreen").on('hidden.bs.modal', function () {
  $(".modal-backdrop").addClass("modal-backdrop-fullscreen");
});

/* .modal-transparent */
.modal-transparent {
  background: transparent;
}
.modal-transparent .modal-content {
  background: transparent;
}
.modal-backdrop.modal-backdrop-transparent {
  background: #ffffff;
}
.modal-backdrop.modal-backdrop-transparent.in {
  opacity: .9;
  filter: alpha(opacity=90);
}

<!-- Button modal transparent -->
<button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#modal-transparent">
  Launch modal transparent
</button>

<!-- Modal transparent -->
<div class="modal modal-transparent fade" id="modal-transparent" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span></button>
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
      </div>
    </div>
  </div>
</div>

// .modal-backdrop classes
$(".modal-transparent").on('show.bs.modal', function () {
  setTimeout( function() {
    $(".modal-backdrop").addClass("modal-backdrop-transparent");
  }, 0);
});
$(".modal-transparent").on('hidden.bs.modal', function () {
  $(".modal-backdrop").addClass("modal-backdrop-transparent");
});