CSS Position of floating element fixed

Question

the blue button (float: right) will not be displayed properly in some cases (depending on resolution and text length).

I'd like to have the blue button at the right hand corner at all times and a line break for the text (if needed).

Any suggestions how to alter the css?

I use bootstrap 3 and this custom code:

.pull-right-not-xs,
.pull-right-not-sm,
.pull-right-not-md,
.pull-right-not-lg {
  float: right;
}

.pull-left-not-xs,
.pull-left-not-sm,
.pull-left-not-md,
.pull-left-not-lg {
  float: left;
}

@media (max-width: 767px) {
  .pull-right-not-xs,
  .pull-left-not-xs {
    float: none;
  }
  .pull-right-xs {
    float: right;
  }
  .pull-left-xs {
    float: left;
  }
}

@media (min-width: 768px) and (max-width: 991px) {
  .pull-right-not-sm,
  .pull-left-not-sm {
    float: none;
  }
  .pull-right-sm {
    float: right;
    margin-right: 6.3;
  }
  .pull-left-sm {
    float: left;
  }
}

@media (min-width: 992px) and (max-width: 1199px) {
  .pull-right-not-md,
  .pull-left-not-md {
    float: none;
  }
  .pull-right-md {
    float: right;
  }
  .pull-left-md {
    float: left;
  }
}

@media (min-width: 1200px) {
  .pull-right-not-lg,
  .pull-left-not-lg {
    float: none;
  }
  .pull-right-lg {
    float: right;
  }
  .pull-left-lg {
    float: left;
  }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<div class="col-sm-6 col-xs-12 item">
  <div class="panel panel-default">
    <div class="panel-heading">
      <h3 class="panel-title">Veranstaltungen <span class="label label-default pull-right">2</span></h3>
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        <a href="/kaimmo/index.jsp?event=19&do=edit" class="list-group-item list-group-item-warning">
                                    25.06.2020 - Betongoldworkshop (BGW) - Zoom-Webinar Deutschland
                                    <span class="pull-right-sm pull-right-md pull-right-lg">
                                        <span style="vertical-align: top; display: inline-block;" class="label label-primary">Korupp, Frederic</span>
                                    </span> 
                                </a>


        <a href="/kaimmo/index.jsp?event=17&do=edit" class="list-group-item list-group-item-warning">
                                    11.06.2020 - Betongoldabend (BGA) - Zoom-Webinar Deutschland
                                    <span class="">
                                        <span class="label label-primary">Ganser, Robin</span>
                                    </span> 
                                </a>


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</div>