Creating a Starry Background in CSS - html

Question

I am making a solar system website in pure code with no images used. The problem is that I can't figure out how to get stars in the background. I'm trying to get something like a yellow spread-out polka dot pattern on a black background. This is my code (repeat div and styling for every other planet).
html,
body {
width: 100%;
height: 100%;
background-color: black;
}
#sun {
position: absolute;
top: 50%;
left: 50%;
height: 200px;
width: 200px;
margin-top: -100px;
margin-left: -100px;
border-color: orange;
border-width: 2px;
border-style: solid;
border-radius: 50%;
box-shadow: 0 0 64px yellow;
background-color: yellow;
}
#mercury {
position: absolute;
top: 0;
left: 50%;
height: 10px;
width: 10px;
margin-left: -5px;
margin-top: -5px;
border-radius: 50%;
background-color: #ffd9b3;
}
#mercury-orbit {
position: absolute;
top: 50%;
left: 50%;
width: 260px;
height: 260px;
margin-top: -130px;
margin-left: -130px;
border-width: 2px;
border-style: dotted;
border-color: white;
border-radius: 50%;
-webkit-animation: spin-right 22s linear infinite;
-moz-animation: spin-right 22s linear infinite;
-ms-animation: spin-right 22s linear infinite;
-o-animation: spin-right 22s linear infinite;
animation: spin-right 22s linear infinite;
}
#-webkit-keyframes spin-right {
100% {
-webkit-transform: rotate(360deg);
-moz-transform: rotate(360deg);
-ms-transform: rotate(360deg);
-o-transform: rotate(360deg);
transform: rotate(360deg);
}
}
#keyframes spin-right {
100% {
-webkit-transform: rotate(360deg);
-moz-transform: rotate(360deg);
-ms-transform: rotate(360deg);
-o-transform: rotate(360deg);
transform: rotate(360deg);
}
}
<div id="sun"></div>
<div id="mercury-orbit">
<div id="mercury"></div>
</div>

Answer 1

From this, a nice starry night.
background-color:black;
background-image:
radial-gradient(white, rgba(255,255,255,.2) 2px, transparent 40px),
radial-gradient(white, rgba(255,255,255,.15) 1px, transparent 30px),
radial-gradient(white, rgba(255,255,255,.1) 2px, transparent 40px),
radial-gradient(rgba(255,255,255,.4), rgba(255,255,255,.1) 2px, transparent 30px);
background-size: 550px 550px, 350px 350px, 250px 250px, 150px 150px;
background-position: 0 0, 40px 60px, 130px 270px, 70px 100px;

Answer 2

I found a pure CSS solution thanks to this code pen. This would make your website look like this - unfortunately I can't copy-paste the entire CSS in, as it's far too long (over 40,000 characters and StackOverflow only permits me to paste 30,000 for a code snippet). The original code was generated with SASS, and compiled, it's ridiculously long.
<div id='stars'></div>
<div id='stars2'></div>
<div id="sun"></div>
<div id="mercury-orbit">
<div id="mercury"></div>
</div>
The SASS code generating these stars:
// n is number of stars required
#function multiple-box-shadow ($n)
$value: '#{random(2000)}px #{random(2000)}px #FFF'
#for $i from 2 through $n
$value: '#{$value} , #{random(2000)}px #{random(2000)}px #FFF'
#return unquote($value)
$shadows-small: multiple-box-shadow(700)
$shadows-medium: multiple-box-shadow(200)
$shadows-big: multiple-box-shadow(100)
#stars
width: 1px
height: 1px
background: transparent
box-shadow: $shadows-small