Is there a way to use SVG as content in a pseudo element ::before or ::after

I would like to use ::before to place SVG images before some selected elements:

#mydiv::before {
  content: '<svg ... code here</svg>';
  display: block;
  width: 22px;
  height: 10px;
  margin: 10px 5px 0 10px;
}

Above code just displays the plaintext.
I checked the spec and there seem to be some restrictions on what content can be. CSS content property solution is preferable.

Yes you can! Just tested this and it works great, this is awesome! It still doesn't work with html, but it does with svg.

SVG URL encoder to format your own SVGs as shown here.

#test::before {
  content: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg'%3E%3Ccircle cx='100' cy='50' r='40' stroke='black' stroke-width='2' fill='red'/%3E%3Cpolyline points='20,20 40,25 60,40 80,120 120,140 200,180' style='fill:none;stroke:black;stroke-width:3'/%3E%3C/svg%3E ");
  width: 200px;
  height: 200px;
}

<div id="test"></div>

You can use the url() CSS function.

#mydiv::before {
  content: url("data:image/svg+xml; utf8, <svg ... code here</svg>");
  display: block;
  width: 22px;
  height: 10px;
  margin: 10px 5px 0 10px;
}

Make sure your SVG doesn't contain any # symbols. Use an encoder like this one.

You can add the SVG as background-image of an empty :after or :before.

Here you go:

.anchor:before {
  display: block;
  content: ' ';
  background-image: url('../images/anchor.svg');
  background-size: 28px 28px;
  height: 28px;
  width: 28px;
}

<div class="author_">Lord Byron</div>

.author_ {  font-family: 'Playfair Display', serif; font-size: 1.25em; font-weight: 700;letter-spacing: 0.25em; font-style: italic;
  position:relative;
  margin-top: -0.5em;
  color: black;
  z-index:1;
  overflow:hidden;
  text-align:center;
 
}


.author_:after{
   left:20px;
  margin:0 -100% 0 0;
  display: inline-block;
  height: 10px;
  content: url(data:image/svg+xml,%0A%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22120px%22%20height%3D%2220px%22%20viewBox%3D%220%200%201200%20200%22%20xmlns%3Axlink%3D%22http%3A%2F%2Fwww.w3.org%2F1999%2Fxlink%22%3E%0A%20%20%3Cpath%20stroke%3D%22black%22%20stroke-width%3D%223%22%20fill%3D%22none%22%20d%3D%22M1145%2085c17%2C7%208%2C24%20-4%2C29%20-12%2C4%20-40%2C6%20-48%2C-8%20-9%2C-15%209%2C-34%2026%2C-42%2017%2C-7%2045%2C-6%2062%2C2%2017%2C9%2019%2C18%2020%2C27%201%2C9%200%2C29%20-27%2C52%20-28%2C23%20-52%2C34%20-102%2C33%20-49%2C0%20-130%2C-31%20-185%2C-50%20-56%2C-18%20-74%2C-21%20-96%2C-23%20-22%2C-2%20-29%2C-2%20-56%2C7%20-27%2C8%20-44%2C17%20-44%2C17%20-13%2C5%20-15%2C7%20-40%2C16%20-25%2C9%20-69%2C14%20-120%2C11%20-51%2C-3%20-126%2C-23%20-181%2C-32%20-54%2C-9%20-105%2C-20%20-148%2C-23%20-42%2C-3%20-71%2C1%20-104%2C5%20-34%2C5%20-65%2C15%20-98%2C22%22%2F%3E%0A%3C%2Fsvg%3E%0A);
}
.author_:before {
  right:20px;
  margin:0 0 0 -100%;
  display: inline-block;
  height: 10px;
  content: url(data:image/svg+xml,%0A%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22120px%22%20height%3D%2220px%22%20viewBox%3D%220%200%201200%20130%22%20xmlns%3Axlink%3D%22http%3A%2F%2Fwww.w3.org%2F1999%2Fxlink%22%3E%0A%20%20%3Cpath%20stroke%3D%22black%22%20stroke-width%3D%223%22%20fill%3D%22none%22%20d%3D%22M55%2068c-17%2C6%20-8%2C23%204%2C28%2012%2C5%2040%2C7%2048%2C-8%209%2C-15%20-9%2C-34%20-26%2C-41%20-17%2C-8%20-45%2C-7%20-62%2C2%20-18%2C8%20-19%2C18%20-20%2C27%20-1%2C9%200%2C29%2027%2C52%2028%2C23%2052%2C33%20102%2C33%2049%2C-1%20130%2C-31%20185%2C-50%2056%2C-19%2074%2C-21%2096%2C-23%2022%2C-2%2029%2C-2%2056%2C6%2027%2C8%2043%2C17%2043%2C17%2014%2C6%2016%2C7%2041%2C16%2025%2C9%2069%2C15%20120%2C11%2051%2C-3%20126%2C-22%20181%2C-32%2054%2C-9%20105%2C-20%20148%2C-23%2042%2C-3%2071%2C1%20104%2C6%2034%2C4%2065%2C14%2098%2C22%22%2F%3E%0A%3C%2Fsvg%3E%0A);
}

	<div class="author_">Lord Byron</div>

Convenient tool for SVG encoding url-encoder

Making use of CSS sprites and data uri gives extra interesting benefits like fast loading and less requests AND we get IE8 support by using image/base64:

Codepen sample using SVG

HTML

<div class="div1"></div>
<div class="div2"></div>

CSS

.div1:after, .div2:after {
  content: '';
  display: block;
  height: 80px;
  width: 80px;
  background-image: url(data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20version%3D%221.1%22%20height%3D%2280%22%20width%3D%22160%22%3E%0D%0A%20%20%3Ccircle%20cx%3D%2240%22%20cy%3D%2240%22%20r%3D%2238%22%20stroke%3D%22black%22%20stroke-width%3D%221%22%20fill%3D%22red%22%20%2F%3E%0D%0A%20%20%3Ccircle%20cx%3D%22120%22%20cy%3D%2240%22%20r%3D%2238%22%20stroke%3D%22black%22%20stroke-width%3D%221%22%20fill%3D%22blue%22%20%2F%3E%0D%0A%3C%2Fsvg%3E);
}
.div2:after {
  background-position: -80px 0;
}

For IE8, change to this:

  background-image: url(data:image/png;base64,data......);

To extend further this topic. In case you want to add Font Awesome 5 icons you need to add some extra CSS.

Icons by default have classes svg-inline--fa and fa-w-*.

There are also modifier classes like fa-lg, fa-rotate-* and other. You need to check svg-with-js.css file and find proper CSS for that.

You need to add your own color to css icon otherwise it will be black by default, for example fill='%23f00' where %23 is encoded #.

h1::before{

  /* svg-inline--fa */
  display:inline-block;
  font-size:inherit;
  height:1em;
  overflow:visible;
  vertical-align:-.125em;
  
  /* fa-w-14 */
  width:.875em;
  
  /* Icon */
  content:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 448 512'%3E%3Cpath fill='%23f00' d='M400 256H152V152.9c0-39.6 31.7-72.5 71.3-72.9 40-.4 72.7 32.1 72.7 72v16c0 13.3 10.7 24 24 24h32c13.3 0 24-10.7 24-24v-16C376 68 307.5-.3 223.5 0 139.5.3 72 69.5 72 153.5V256H48c-26.5 0-48 21.5-48 48v160c0 26.5 21.5 48 48 48h352c26.5 0 48-21.5 48-48V304c0-26.5-21.5-48-48-48zM264 408c0 22.1-17.9 40-40 40s-40-17.9-40-40v-48c0-22.1 17.9-40 40-40s40 17.9 40 40v48z'%3E%3C/path%3E%3C/svg%3E");
  
  /* Margin */
  margin-right:.75rem;
}

<h1>Lorem Ipsum</h1>

Be careful all of the other answers have some problem in IE.

Lets have this situation - button with prepended icon. All browsers handles this correctly, but IE takes the width of the element and scales the before content to fit it. JSFiddle

#mydiv1 { width: 200px; height: 30px; background: green; }
#mydiv1:before {
    content: url("data:url or /standard/url.svg");
}

Solution is to set size to before element and leave it where it is:

#mydiv2 { width: 200px; height: 30px; background: green; }
#mydiv2:before {
    content: url("data:url or /standard/url.svg");
    display: inline-block;
    width: 16px; //only one size is alright, IE scales uniformly to fit it
}

The background-image + background-size solutions works as well, but is little unhandy, since you have to specify the same sizes twice.

The result in IE11:

Although this was many years ago, I'd like to also share this.

The answers above are correct, you can directly attach the encoded svg string into the css content property. For those having any issues with the URL it may be due to spaces and characters not valid for such, in that case paste your decoded SVG code into: https://mothereff.in/url

Use the encoded SVG URL and it should work fine. Incorrect & Correct Examples:

#incorrect::before {
  content: url(
    data:image/svg + xml,
    <svgid="Layer_1"data-name="Layer 1"xmlns="http://www.w3.org/2000/svg"viewBox="0 0 15.37 188.41"><defs><style>.cls-1{fill:#aeadad;}</style></defs><circleclass="cls-1"cx="7.69"cy="7.69"r="7.69"/><rectclass="cls-1"x="6.69"y="27.72"width="2"height="160.69"/></svg>
  );
}

#correct::before {
  content: url(data:image/svg+xml,%0A%3Csvg%20id%3D%22Layer%5f1%22%20data-name%3D%22Layer%201%22%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%2015.37%20188.41%22%3E%3Cdefs%3E%3Cstyle%3E.cls-1%7Bfill%3A%23aeadad%3B%7D%3C%2Fstyle%3E%3C%2Fdefs%3E%3Ccircle%20class%3D%22cls-1%22%20cx%3D%227.69%22%20cy%3D%227.69%22%20r%3D%227.69%22%2F%3E%3Crect%20class%3D%22cls-1%22%20x%3D%226.69%22%20y%3D%2227.72%22%20width%3D%222%22%20height%3D%22160.69%22%2F%3E%3C%2Fsvg%3E%0A);
}

I just today noticed that a newspaper here used direct injection of the SVG into the ::before and ::after pseudo-elements to render stylized quotes for highlighted content in the article. I tried to find that paper's CMS via whatcms.org but to no avail. I can say however that the owner newspaper - a large national, even international, paper uses a CMS called DM Polopoly.

It seems so much more laborious to enter SVG data into the content element rather than blank the content and use the SVG as a background image. I wonder why they chose this method - what advantage went with this. I've seen some people on Google links who said it made it easy to manipulate the SVG image on hovering upon the pseudo-element . . . But I saw no killer example of this 'benefit'.

This article has a simpler method for inserting the SVG as content. It uses a zoom property to get size adjustment for the image.

.myDiv {
  display: flex;
  align-items: center;
}

.myDiv:before {
  display: inline-block;
  content: url(./dog.svg);
  margin-right: 15px;
  width: 10px;
}