It is common to show how many notifications one has in your site. Usually these kind of notifications are shown as small circles above an icon like envelope. If you add some dynamic effects to these bulbs, they would look more interesting. See demo to find various examples of this.


HTML
<!-- This script got from www.devanswer.com -->
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/meyer-reset/2.0/reset.min.css">
<nav id="sidebar">
<ul class="dots">
<li>
<a href="#">
<span class="glyphicon glyphicon-user"><mark>23</mark></span>
</a>
</li>
<li>
<a href="#">
<span class="glyphicon glyphicon-envelope"><mark class="big swing">7</mark></span>
</a>
</li>
<li>
<a href="#">
<span class="glyphicon glyphicon-time"><mark class="rubberBand">99</mark></span>
</a>
</li>
<li>
<a href="#">
<span class="glyphicon glyphicon-list-alt"></span>
</a>
</li>
<li>
<a href="#">
<span class="glyphicon glyphicon-calendar"><mark class="green wobble">99+</mark></span>
</a>
</li>
<li>
<a href="#">
<span class="glyphicon glyphicon-random"><mark class="blue tada">13</mark></span>
</a>
</li>
</ul>
</nav>
<main>
<h1>Hello world!</h1>
<p>Move cursor over icon on the left to animate marks</p>
<ul>
<li>To change mark color use following class's: <code>.green, .blue</code></li>
<li>Marks are prepare to handle with two-digit numbers from <code>0 to 99</code>. If your number is greater than 99 use logic to display <code>99+</code>.</li>
</ul><div id="bcl"><a style="font-size:8pt;text-decoration:none;" href="http://www.devanswer.com">Developers Answer</a></div>
                        

CSS
@import url("https://fonts.googleapis.com/css?family=Roboto:400,700");
@import url("https://fonts.googleapis.com/css?family=Merriweather+Sans:400,400italic");
@import url("https://netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap-glyphicons.css");

main {
  margin-left: 100px;
  padding: 20px;
}

h1 {
  font-family: 'Merriweather Sans', sans-serif;
  font-weight: 400;
  font-size: 30px;
}
nav#sidebar {
  background-color: #34495e;
  position: fixed;
  width: 100px;
  height: 100%;
}
ul.dots * {
  /* disable border-box from bootstrap */
  box-sizing: content-box;
  list-style-type: none;  
}
ul.dots a {
  text-decoration: none;
  font-size: 20px;
  color: #34495e;
}
ul.dots a:hover {
  text-decoration: none;
  font-size: 20px;
  color: #bdc3c7;
}
ul.dots li {
  display: box;
  position: relative;
  width: 100%;
  padding: 10px 0 ;  
}
ul.dots li:hover {
  background: #2c3e50;
}
ul.dots li span {
  display: block;
  border-radius: 30px; 
  background-color: #FFF;
  box-shadow: 1px 1px 5px #808080;  
  padding: 10px;
  width: 30px;
  height: 30px;
  margin: 0 auto;
  line-height: 30px;
  text-align: center;
  position: relative;
}
ul.dots li mark {
  border-radius: 20px;   
  border: 2px solid #FFF;
  width: 20px;
  height: 20px;  
  background-color: #FF6B6B;
  position: absolute;
  top: -5px;
  left: -10px;
  font-size: 10px;
  line-height: 20px;
  font-family: 'Roboto', sans-serif;
  font-weight: 400;
  color: #FFF;
  font-weight: 700;
}
ul.dots li mark.big {
  width: 30px;
  height: 30px;
  border-radius: 30px;
  line-height: 30px;  
  font-size: 16px;  
  top: -10px;
  left: -15px;
}
ul.dots li mark.green {
  background-color: #27ae60;
}
ul.dots li mark.blue {
  background-color: #3498db;
}
ul.dots > li > a > span > mark {
  -webkit-animation-name: bounceIn;
          animation-name: bounceIn;
  -webkit-transform-origin: center bottom;
          transform-origin: center bottom;
  -webkit-animation-duration: 1s;
          animation-duration: 1s;
  -webkit-animation-fill-mode: both;
          animation-fill-mode: both;   
-webkit-animation-iteration-count: 1;
        animation-iteration-count: 1;  
}
ul.dots > li:hover > a > span > mark {
  -webkit-animation-name: bounce;
          animation-name: bounce;
}
ul.dots > li:hover > a > span > mark.rubberBand {
  -webkit-animation-name: rubberBand;
          animation-name: rubberBand;
}

ul.dots > li:hover > a > span > mark.swing {
  -webkit-transform-origin: top center;
          transform-origin: top center;
  -webkit-animation-name: swing;
          animation-name: swing;
}
ul.dots > li:hover > a > span > mark.tada {
  -webkit-animation-name: tada;
          animation-name: tada;
}
ul.dots > li:hover > a > span > mark.wobble {
  -webkit-animation-name: wobble;
          animation-name: wobble;
}
li {
  list-style-type: circle;
}

code {
  background: #ecf0f1;
}

/* animation keyframes */
@-webkit-keyframes bounce {
  0%, 20%, 53%, 80%, 100% {
    transition-timing-function: cubic-bezier(0.215, 0.610, 0.355, 1.000);
    -webkit-transform: translate3d(0,0,0);
            transform: translate3d(0,0,0);
  }

  40%, 43% {
    transition-timing-function: cubic-bezier(0.755, 0.050, 0.855, 0.060);
    -webkit-transform: translate3d(0, -30px, 0);
            transform: translate3d(0, -30px, 0);
  }

  70% {
    transition-timing-function: cubic-bezier(0.755, 0.050, 0.855, 0.060);
    -webkit-transform: translate3d(0, -15px, 0);
            transform: translate3d(0, -15px, 0);
  }

  90% {
    -webkit-transform: translate3d(0,-4px,0);
            transform: translate3d(0,-4px,0);
  }
}

@keyframes bounce {
  0%, 20%, 53%, 80%, 100% {
    transition-timing-function: cubic-bezier(0.215, 0.610, 0.355, 1.000);
    -webkit-transform: translate3d(0,0,0);
            transform: translate3d(0,0,0);
  }

  40%, 43% {
    transition-timing-function: cubic-bezier(0.755, 0.050, 0.855, 0.060);
    -webkit-transform: translate3d(0, -30px, 0);
            transform: translate3d(0, -30px, 0);
  }

  70% {
    transition-timing-function: cubic-bezier(0.755, 0.050, 0.855, 0.060);
    -webkit-transform: translate3d(0, -15px, 0);
            transform: translate3d(0, -15px, 0);
  }

  90% {
    -webkit-transform: translate3d(0,-4px,0);
            transform: translate3d(0,-4px,0);
  }
}

@-webkit-keyframes bounceIn {
  0%, 20%, 40%, 60%, 80%, 100% {
    transition-timing-function: cubic-bezier(0.215, 0.610, 0.355, 1.000);
  }

  0% {
    opacity: 0;
    -webkit-transform: scale3d(.3, .3, .3);
            transform: scale3d(.3, .3, .3);
  }

  20% {
    -webkit-transform: scale3d(1.1, 1.1, 1.1);
            transform: scale3d(1.1, 1.1, 1.1);
  }

  40% {
    -webkit-transform: scale3d(.9, .9, .9);
            transform: scale3d(.9, .9, .9);
  }

  60% {
    opacity: 1;
    -webkit-transform: scale3d(1.03, 1.03, 1.03);
            transform: scale3d(1.03, 1.03, 1.03);
  }

  80% {
    -webkit-transform: scale3d(.97, .97, .97);
            transform: scale3d(.97, .97, .97);
  }

  100% {
    opacity: 1;
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }
}

@keyframes bounceIn {
  0%, 20%, 40%, 60%, 80%, 100% {
    transition-timing-function: cubic-bezier(0.215, 0.610, 0.355, 1.000);
  }

  0% {
    opacity: 1;
    -webkit-transform: scale3d(.3, .3, .3);
            transform: scale3d(.3, .3, .3);
  }

  20% {
    -webkit-transform: scale3d(1.1, 1.1, 1.1);
            transform: scale3d(1.1, 1.1, 1.1);
  }

  40% {
    -webkit-transform: scale3d(.9, .9, .9);
            transform: scale3d(.9, .9, .9);
  }

  60% {
    opacity: 1;
    -webkit-transform: scale3d(1.03, 1.03, 1.03);
            transform: scale3d(1.03, 1.03, 1.03);
  }

  80% {
    -webkit-transform: scale3d(.97, .97, .97);
            transform: scale3d(.97, .97, .97);
  }

  100% {
    opacity: 1;
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }
}
@-webkit-keyframes rubberBand {
  0% {
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }

  30% {
    -webkit-transform: scale3d(1.25, 0.75, 1);
            transform: scale3d(1.25, 0.75, 1);
  }

  40% {
    -webkit-transform: scale3d(0.75, 1.25, 1);
            transform: scale3d(0.75, 1.25, 1);
  }

  50% {
    -webkit-transform: scale3d(1.15, 0.85, 1);
            transform: scale3d(1.15, 0.85, 1);
  }

  65% {
    -webkit-transform: scale3d(.95, 1.05, 1);
            transform: scale3d(.95, 1.05, 1);
  }

  75% {
    -webkit-transform: scale3d(1.05, .95, 1);
            transform: scale3d(1.05, .95, 1);
  }

  100% {
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }
}

@keyframes rubberBand {
  0% {
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }

  30% {
    -webkit-transform: scale3d(1.25, 0.75, 1);
            transform: scale3d(1.25, 0.75, 1);
  }

  40% {
    -webkit-transform: scale3d(0.75, 1.25, 1);
            transform: scale3d(0.75, 1.25, 1);
  }

  50% {
    -webkit-transform: scale3d(1.15, 0.85, 1);
            transform: scale3d(1.15, 0.85, 1);
  }

  65% {
    -webkit-transform: scale3d(.95, 1.05, 1);
            transform: scale3d(.95, 1.05, 1);
  }

  75% {
    -webkit-transform: scale3d(1.05, .95, 1);
            transform: scale3d(1.05, .95, 1);
  }

  100% {
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }
}
@-webkit-keyframes swing {
  20% {
    -webkit-transform: rotate3d(0, 0, 1, 15deg);
            transform: rotate3d(0, 0, 1, 15deg);
  }

  40% {
    -webkit-transform: rotate3d(0, 0, 1, -10deg);
            transform: rotate3d(0, 0, 1, -10deg);
  }

  60% {
    -webkit-transform: rotate3d(0, 0, 1, 5deg);
            transform: rotate3d(0, 0, 1, 5deg);
  }

  80% {
    -webkit-transform: rotate3d(0, 0, 1, -5deg);
            transform: rotate3d(0, 0, 1, -5deg);
  }

  100% {
    -webkit-transform: rotate3d(0, 0, 1, 0deg);
            transform: rotate3d(0, 0, 1, 0deg);
  }
}

@keyframes swing {
  20% {
    -webkit-transform: rotate3d(0, 0, 1, 15deg);
            transform: rotate3d(0, 0, 1, 15deg);
  }

  40% {
    -webkit-transform: rotate3d(0, 0, 1, -10deg);
            transform: rotate3d(0, 0, 1, -10deg);
  }

  60% {
    -webkit-transform: rotate3d(0, 0, 1, 5deg);
            transform: rotate3d(0, 0, 1, 5deg);
  }

  80% {
    -webkit-transform: rotate3d(0, 0, 1, -5deg);
            transform: rotate3d(0, 0, 1, -5deg);
  }

  100% {
    -webkit-transform: rotate3d(0, 0, 1, 0deg);
            transform: rotate3d(0, 0, 1, 0deg);
  }
}

@-webkit-keyframes tada {
  0% {
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }

  10%, 20% {
    -webkit-transform: scale3d(.9, .9, .9) rotate3d(0, 0, 1, -3deg);
            transform: scale3d(.9, .9, .9) rotate3d(0, 0, 1, -3deg);
  }

  30%, 50%, 70%, 90% {
    -webkit-transform: scale3d(1.1, 1.1, 1.1) rotate3d(0, 0, 1, 3deg);
            transform: scale3d(1.1, 1.1, 1.1) rotate3d(0, 0, 1, 3deg);
  }

  40%, 60%, 80% {
    -webkit-transform: scale3d(1.1, 1.1, 1.1) rotate3d(0, 0, 1, -3deg);
            transform: scale3d(1.1, 1.1, 1.1) rotate3d(0, 0, 1, -3deg);
  }

  100% {
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }
}

@keyframes tada {
  0% {
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }

  10%, 20% {
    -webkit-transform: scale3d(.9, .9, .9) rotate3d(0, 0, 1, -3deg);
            transform: scale3d(.9, .9, .9) rotate3d(0, 0, 1, -3deg);
  }

  30%, 50%, 70%, 90% {
    -webkit-transform: scale3d(1.1, 1.1, 1.1) rotate3d(0, 0, 1, 3deg);
            transform: scale3d(1.1, 1.1, 1.1) rotate3d(0, 0, 1, 3deg);
  }

  40%, 60%, 80% {
    -webkit-transform: scale3d(1.1, 1.1, 1.1) rotate3d(0, 0, 1, -3deg);
            transform: scale3d(1.1, 1.1, 1.1) rotate3d(0, 0, 1, -3deg);
  }

  100% {
    -webkit-transform: scale3d(1, 1, 1);
            transform: scale3d(1, 1, 1);
  }
}

@-webkit-keyframes wobble {
  0% {
    -webkit-transform: none;
            transform: none;
  }

  15% {
    -webkit-transform: translate3d(-25%, 0, 0) rotate3d(0, 0, 1, -5deg);
            transform: translate3d(-25%, 0, 0) rotate3d(0, 0, 1, -5deg);
  }

  30% {
    -webkit-transform: translate3d(20%, 0, 0) rotate3d(0, 0, 1, 3deg);
            transform: translate3d(20%, 0, 0) rotate3d(0, 0, 1, 3deg);
  }

  45% {
    -webkit-transform: translate3d(-15%, 0, 0) rotate3d(0, 0, 1, -3deg);
            transform: translate3d(-15%, 0, 0) rotate3d(0, 0, 1, -3deg);
  }

  60% {
    -webkit-transform: translate3d(10%, 0, 0) rotate3d(0, 0, 1, 2deg);
            transform: translate3d(10%, 0, 0) rotate3d(0, 0, 1, 2deg);
  }

  75% {
    -webkit-transform: translate3d(-5%, 0, 0) rotate3d(0, 0, 1, -1deg);
            transform: translate3d(-5%, 0, 0) rotate3d(0, 0, 1, -1deg);
  }

  100% {
    -webkit-transform: none;
            transform: none;
  }
}

@keyframes wobble {
  0% {
    -webkit-transform: none;
            transform: none;
  }

  15% {
    -webkit-transform: translate3d(-25%, 0, 0) rotate3d(0, 0, 1, -5deg);
            transform: translate3d(-25%, 0, 0) rotate3d(0, 0, 1, -5deg);
  }

  30% {
    -webkit-transform: translate3d(20%, 0, 0) rotate3d(0, 0, 1, 3deg);
            transform: translate3d(20%, 0, 0) rotate3d(0, 0, 1, 3deg);
  }

  45% {
    -webkit-transform: translate3d(-15%, 0, 0) rotate3d(0, 0, 1, -3deg);
            transform: translate3d(-15%, 0, 0) rotate3d(0, 0, 1, -3deg);
  }

  60% {
    -webkit-transform: translate3d(10%, 0, 0) rotate3d(0, 0, 1, 2deg);
            transform: translate3d(10%, 0, 0) rotate3d(0, 0, 1, 2deg);
  }

  75% {
    -webkit-transform: translate3d(-5%, 0, 0) rotate3d(0, 0, 1, -1deg);
            transform: translate3d(-5%, 0, 0) rotate3d(0, 0, 1, -1deg);
  }

  100% {
    -webkit-transform: none;
            transform: none;
  }
}