Check out example codes for "css fade out". It will help you in understanding the concepts better.

Code Example 1

/* Just add .fade-in class to element */

.fade-in {
	animation: fadeIn 2s;
  	opacity: 1;
}

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

Code Example 2

.fade-out {  animation: fadeOut ease 8s;  -webkit-animation: fadeOut ease 8s;  -moz-animation: fadeOut ease 8s;  -o-animation: fadeOut ease 8s;  -ms-animation: fadeOut ease 8s;}@keyframes fadeOut {  0% {    opacity:1;  }  100% {    opacity:0;  }}@-moz-keyframes fadeOut {  0% {    opacity:1;  }  100% {    opacity:0;  }}@-webkit-keyframes fadeOut {  0% {    opacity:1;  }  100% {    opacity:0;  }}@-o-keyframes fadeOut {  0% {    opacity:1;  }  100% {    opacity:0;  }}@-ms-keyframes fadeOut {  0% {    opacity:1;  }  100% {    opacity:0;}

Code Example 3

/* Answer to: "css fade out" */

/*
  With the code below, all you have to do is use JavaScript to
  give the element ".hide-opacity" and it'll fade-out.

  Feel free to edit this code so it works on hover, focus, active
  or any other special selector possible with CSS and of course
  feel free to use this code with your JavaScript too!
*/

.successfully-saved {
    color: #FFFFFF;
    text-align: center;

    -webkit-transition: opacity 3s ease-in-out;
    -moz-transition: opacity 3s ease-in-out;
    -ms-transition: opacity 3s ease-in-out;
    -o-transition: opacity 3s ease-in-out;
     opacity: 1;
}

.successfully-saved.hide-opacity {
    opacity: 0;
}

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