How to make the last keyframe of your animation “stay” after animation is finished

Remove the dual declaration for animation-fill-mode is just forwards :

.fadein{    
  animation:fadein 1.5s;
  animation-timing-function:linear;
  animation-delay:1s;
  animation-fill-mode:forwards;
  animation-iteration-count: 1;
  -webkit-animation-iteration-count: 1;
  -webkit-animation:fadein 1.5s;
  -webkit-animation-timing-function:linear;
  -webkit-animation-delay:1s;
  -webkit-animation-fill-mode: forwards;
}

The demo http://jsfiddle.net/DR9Lu/6/