Bootstrap 3 smooth accordion transitions

I' am using a Bootstrap 3 accordion. Everything works fine except the transition is not smooth. It's like jumping transitions. How can I have a smooth transition? HTML ``` <div class="panel" id="<?php echo $id; ?>"> <div class="panel-title"><?php the_title(); ?></div> <div id="collapse-<?php echo $id; ?>" class="panel-collapse collapse" style="overflow:hidden; display: block;"> <div class="panel-body"><?php the_content(); ?></div> </div> <a data-toggle="collapse" data-parent="#accordion" href="#collapse-<?php echo $id; ?>" class="collapsed read_more" id="btn-collapse-<?php echo $id; ?>">Read More &raquo;</a> </div> ``` JS ``` $('.panel-collapse').on('shown.bs.collapse', function () { var collapse_id = $( this ).attr("id"); $(".panel > #btn-"+collapse_id).text("Close"); }); $('.panel-collapse').on('hidden.bs.collapse', function () { var collapse_id = $( this ).attr("id"); $(".panel > #btn-"+collapse_id).text("Read More"); }); ``` I did follow everything as on official site. What I have tried: This tranisiton CSS on collapsing Class ``` .panel .collapsing{ height: 100px !important; -moz-transition : height 5s; -webkit-transition : height 5s; -o-transition : height 5s; transition : height 5s; } ```