Animate multiple elements sequentially using only CSS3 + SASS [duplicate] - html

Question

I was trying to make a gradual fadein using normal CSS and no jquery on a list so it can fade in one-by-one. However, I only know how to do it in a limited amount of list. How do I loop the css so no matter how much list I have it still works.
Here is what I have done:
.ladder {
opacity: 0;
-webkit-animation: fadeIn 0.9s 1;
animation: fadeIn 0.9s 1;
-webkit-animation-fill-mode: forwards;
animation-fill-mode: forwards;
}
.ladder:nth-child(5n+1) {
-webkit-animation-delay: 0.2s;
animation-delay: 0.2s;
}
.ladder:nth-child(5n+2) {
-webkit-animation-delay: 0.4s;
animation-delay: 0.4s;
}
.ladder:nth-child(5n+3) {
-webkit-animation-delay: 0.6s;
animation-delay: 0.6s;
}
.ladder:nth-child(5n+4) {
-webkit-animation-delay: 0.8s;
animation-delay: 0.8s;
}
.ladder:nth-child(5n+5) {
-webkit-animation-delay: 1.0s;
animation-delay: 1.0s;
}
#-webkit-keyframes fadeIn {
0% {
opacity: 0.0;
}
100% {
opacity: 1.0;
}
}
#keyframes fadeIn {
0% {
opacity: 0.0;
}
100% {
opacity: 1.0;
}
}
<li class="ladder">A</li>
<li class="ladder">B</li>
<li class="ladder">C</li>
<li class="ladder">D</li>
<li class="ladder">E</li>
My question: How to make the css to work on no matter how much list there is.

Answer 1

Here is an idea using CSS variable that allow you to reduce the code. It's not generic but it's more easier to append a simple inline CSS to each li than writing complex CSS:
.ladder {
opacity: 0;
animation: fadeIn 1s var(--d) forwards;
}
#keyframes fadeIn {
100% {
opacity: 1;
}
}
<ul>
<li style="--d:0s" class="ladder">A</li>
<li style="--d:0.2s" class="ladder">B</li>
<li style="--d:0.4s" class="ladder">C</li>
<li style="--d:0.6s" class="ladder">D</li>
<li style="--d:0.8s" class="ladder">E</li>
</ul>
Here is another idea where you can apply an animation on the ul:
ul {
position:relative;
}
ul:before {
content:"";
position:absolute;
top:-20px;
bottom:0;
left:0;
right:0;
background:linear-gradient(to bottom,transparent,#fff 20px);
animation:fadeIn 2s forwards
}
#keyframes fadeIn {
0% {
top:-10px;
}
100% {
top: 100%;
}
}
<ul>
<li>A</li>
<li>B</li>
<li>C</li>
<li>D</li>
<li>E</li>
</ul>