ЗВЁЗДНОЕ НЕБО С ОБЛАКАМИ НА CSS3

В любое нужное место на странице вставьте:

<div class="stars"></div>
<div class="twinkling"></div>
<div class="clouds"></div>

<div class="stars"></div>
<div class="twinkling"></div>
<div class="clouds"></div>
 

2#: В самый низ вашего CSS поместите:

@keyframes move-twink-back {
from {
background-position: 0 0;
}

to {
background-position: -10000px 5000px;
}
}

@-webkit-keyframes move-twink-back {
from {
background-position: 0 0;
}

to {
background-position: -10000px 5000px;
}
}

@-moz-keyframes move-twink-back {
from {
background-position: 0 0;
}

to {
background-position: -10000px 5000px;
}
}

@-ms-keyframes move-twink-back {
from {
background-position: 0 0;
}

to {
background-position: -10000px 5000px;
}
}

@keyframes move-clouds-back {
from {
background-position: 0 0;
}

to {
background-position: 10000px 0;
}
}

@-webkit-keyframes move-clouds-back {
from {
background-position: 0 0;
}

to {
background-position: 10000px 0;
}
}

@-moz-keyframes move-clouds-back {
from {
background-position: 0 0;
}

to {
background-position: 10000px 0;
}
}

@-ms-keyframes move-clouds-back {
from {
background-position: 0;
}

to {
background-position: 10000px 0;
}
}

.stars,.twinkling,.clouds {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
width: 100%;
height: 100%;
display: block;
}

.stars {
background: #000 url(/img/stars.png) repeat top center;
z-index: 0;
}

.twinkling {
background: transparent url(/img/twinkling.png) repeat top center;
z-index: 1;
-moz-animation: move-twink-back 200s linear infinite;
-ms-animation: move-twink-back 200s linear infinite;
-o-animation: move-twink-back 200s linear infinite;
-webkit-animation: move-twink-back 200s linear infinite;
animation: move-twink-back 200s linear infinite;
}

.clouds {
background: transparent url(/img/clouds.png) repeat top center;
z-index: 3;
-moz-animation: move-clouds-back 200s linear infinite;
-ms-animation: move-clouds-back 200s linear infinite;
-o-animation: move-clouds-back 200s linear infinite;
-webkit-animation: move-clouds-back 200s linear infinite;
animation: move-clouds-back 200s linear infinite;
}

@keyframes move-twink-back {
from {
background-position: 0 0;
}
 
to {
background-position: -10000px 5000px;
}
}
 
@-webkit-keyframes move-twink-back {
from {
background-position: 0 0;
}
 
to {
background-position: -10000px 5000px;
}
}
 
@-moz-keyframes move-twink-back {
from {
background-position: 0 0;
}
 
to {
background-position: -10000px 5000px;
}
}
 
@-ms-keyframes move-twink-back {
from {
background-position: 0 0;
}
 
to {
background-position: -10000px 5000px;
}
}
 
@keyframes move-clouds-back {
from {
background-position: 0 0;
}
 
to {
background-position: 10000px 0;
}
}
 
@-webkit-keyframes move-clouds-back {
from {
background-position: 0 0;
}
 
to {
background-position: 10000px 0;
}
}
 
@-moz-keyframes move-clouds-back {
from {
background-position: 0 0;
}
 
to {
background-position: 10000px 0;
}
}
 
@-ms-keyframes move-clouds-back {
from {
background-position: 0;
}
 
to {
background-position: 10000px 0;
}
}
 
.stars,.twinkling,.clouds {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
width: 100%;
height: 100%;
display: block;
}
 
.stars {
background: #000 url(/img/stars.png) repeat top center;
z-index: 0;
}
 
.twinkling {
background: transparent url(/img/twinkling.png) repeat top center;
z-index: 1;
-moz-animation: move-twink-back 200s linear infinite;
-ms-animation: move-twink-back 200s linear infinite;
-o-animation: move-twink-back 200s linear infinite;
-webkit-animation: move-twink-back 200s linear infinite;
animation: move-twink-back 200s linear infinite;
}
 
.clouds {
background: transparent url(/img/clouds.png) repeat top center;
z-index: 3;
-moz-animation: move-clouds-back 200s linear infinite;
-ms-animation: move-clouds-back 200s linear infinite;
-o-animation: move-clouds-back 200s linear infinite;
-webkit-animation: move-clouds-back 200s linear infinite;
animation: move-clouds-back 200s linear infinite;
}
Три картинки из прикреплённого архива залейте в папку img