Why CSS3 Animation is not working?

Question

Can someone help me to find out why animation on <h5> element doesn't work?

#hero h5 {
  animation: fadein 2s;
  -moz-animation: fadein 2s; /* Firefox */
  -webkit-animation: fadein 2s; /* Safari and Chrome */
  -o-animation: fadein 2s; /* Opera */
  font-weight: strong;
  font-size: 28px; 
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<section id="hero">
    <div class="content">
        <div class="container">
            <div class="row">
                <h5>Lorem Ipsum Demo Title</h5>
            </div><!-- row -->
        </div> <!-- container -->
    </div> <!-- content -->
</section><!-- section -->      

Answer 1

You are calling fadein animation in your code but you haven't defined it anywhere.

CSS3 animations are defined with @keyframes rule. More Information about CSS3 animations is Here.

Add following css:

@keyframes fadein {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

#hero h5 {
  animation: fadein 2s;
  -moz-animation: fadein 2s; /* Firefox */
  -webkit-animation: fadein 2s; /* Safari and Chrome */
  -o-animation: fadein 2s; /* Opera */
  font-weight: strong;
  font-size: 28px; 
}

@keyframes fadein {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<section id="hero">
  <div class="content">
    <div class="container">
      <div class="row">
        <h5>Lorem Ipsum Demo Title</h5>
      </div><!-- row -->
    </div> <!-- container -->
  </div> <!-- content -->
</section><!-- section -->      

Answer 2

#hero h5 {
     font-weight: strong;
     font-size: 28px; 
 -webkit-animation-delay: 0.7s;
  -moz-animation-delay: 0.7s;
  animation-delay: 0.7s;
}

@-webkit-keyframes fadeIn { from { opacity:0; } to { opacity:1; } }
@-moz-keyframes fadeIn { from { opacity:0; } to { opacity:1; } }
@keyframes fadeIn { from { opacity:0; } to { opacity:1; } }

.fade-in {
  opacity:0;
  -webkit-animation:fadeIn ease-in 1;
  -moz-animation:fadeIn ease-in 1;
  animation:fadeIn ease-in 1;

  -webkit-animation-fill-mode:forwards;
  -moz-animation-fill-mode:forwards;
  animation-fill-mode:forwards;

  -webkit-animation-duration:1s;
  -moz-animation-duration:1s;
  animation-duration:1s;
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<section id="hero">
        <div class="content">
            <div class="container">
                <div class="row">
                <h5 class="fade-in">Lorem Ipsum Demo Title</h5>
 
                </div><!-- row -->
            </div> <!-- container -->
        </div> <!-- content -->
</section><!-- section -->   




  

Answer 3

You must define a animation named fadeIn - as shown below.

Currently, you are using an animation but you have never created it.

@keyframes fadeIn {
    0% {
        transform: translate(0,0)
    }
    30% {
        transform: translate(5px,0)
    }
    55% {
        transform: translate(0,0)
    }
   80% {
        transform: translate(5px,0)
    }
    100% {
        transform: translate(0,0)
    }
}