It is possible to set an SVG background image using only CSS. To do that you’ll need to convert SVG code to the Data URL string.

Data URLs, URLs prefixed with the data: scheme, allow content creators to embed small files inline in documents.

MDN

Browser support for Data URLs on CanIUse: https://caniuse.com/#feat=mdn-http_data-url_css_files

Example

Say we have the initial SVG code:

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 426.667 426.667" style="enable-background:new 0 0 426.667 426.667;" xml:space="preserve">
  <g>
    <g>
      <g>
        <path d="M213.333,106.667c-58.88,0-106.667,47.787-106.667,106.667S154.453,320,213.333,320S320,272.213,320,213.333     S272.213,106.667,213.333,106.667z" fill="gold"/>
        <path d="M213.333,0C95.467,0,0,95.467,0,213.333s95.467,213.333,213.333,213.333S426.667,331.2,426.667,213.333     S331.2,0,213.333,0z M213.333,384c-94.293,0-170.667-76.373-170.667-170.667S119.04,42.667,213.333,42.667     S384,119.04,384,213.333S307.627,384,213.333,384z" fill="gold"/>
      </g>
    </g>
  </g>
</svg>

To convert it to Data URL string use the URL-encoder for SVG online tool. So the end code will look as follows.

Encoded SVG string:

data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' version='1.1' x='0px' y='0px' viewBox='0 0 426.667 426.667' style='enable-background:new 0 0 426.667 426.667;' xml:space='preserve'%3E%3Cg%3E%3Cg%3E%3Cg%3E%3Cpath d='M213.333,106.667c-58.88,0-106.667,47.787-106.667,106.667S154.453,320,213.333,320S320,272.213,320,213.333 S272.213,106.667,213.333,106.667z' fill='gold'/%3E%3Cpath d='M213.333,0C95.467,0,0,95.467,0,213.333s95.467,213.333,213.333,213.333S426.667,331.2,426.667,213.333 S331.2,0,213.333,0z M213.333,384c-94.293,0-170.667-76.373-170.667-170.667S119.04,42.667,213.333,42.667 S384,119.04,384,213.333S307.627,384,213.333,384z' fill='gold'/%3E%3C/g%3E%3C/g%3E%3C/g%3E%3C/svg%3E

Once SVG code is converted to an encoded string it then can be then set via background property in CSS.

HTML:

<div class=”svg-background”></div>

CSS:

.svg-background {
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' version='1.1' x='0px' y='0px' viewBox='0 0 426.667 426.667' style='enable-background:new 0 0 426.667 426.667;' xml:space='preserve'%3E%3Cg%3E%3Cg%3E%3Cg%3E%3Cpath d='M213.333,106.667c-58.88,0-106.667,47.787-106.667,106.667S154.453,320,213.333,320S320,272.213,320,213.333 S272.213,106.667,213.333,106.667z' fill='gold'/%3E%3Cpath d='M213.333,0C95.467,0,0,95.467,0,213.333s95.467,213.333,213.333,213.333S426.667,331.2,426.667,213.333 S331.2,0,213.333,0z M213.333,384c-94.293,0-170.667-76.373-170.667-170.667S119.04,42.667,213.333,42.667 S384,119.04,384,213.333S307.627,384,213.333,384z' fill='gold'/%3E%3C/g%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}

Result:

See the Pen SVG as background image with hover by Nikita Hlopov (@nikitahl) on CodePen.

Use cases

This technique is quite useful when you don’t have access to markup (HTML) but you can edit CSS. This is a quite common case for WordPress sites.

Lists

Say you have an existing list with bullets. And you need to set a custom symbol for list items. You can use the list-style-image property which accepts the url() value where you can pass encoded SVG image.

HTML:

<ul>
  <li>Banana</li>
  <li>Apple</li>
  <li>Kiwi</li>
</ul>

CSS:

li {
  list-style-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' version='1.1' x='0px' y='0px' viewBox='0 0 426.667 426.667' style='enable-background:new 0 0 426.667 426.667;' xml:space='preserve'%3E%3Cg%3E%3Cg%3E%3Cg%3E%3Cpath d='M213.333,106.667c-58.88,0-106.667,47.787-106.667,106.667S154.453,320,213.333,320S320,272.213,320,213.333 S272.213,106.667,213.333,106.667z' fill='gold'/%3E%3Cpath d='M213.333,0C95.467,0,0,95.467,0,213.333s95.467,213.333,213.333,213.333S426.667,331.2,426.667,213.333 S331.2,0,213.333,0z M213.333,384c-94.293,0-170.667-76.373-170.667-170.667S119.04,42.667,213.333,42.667 S384,119.04,384,213.333S307.627,384,213.333,384z' fill='gold'/%3E%3C/g%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}

Hover effects

Another great part of the SVG background image is that you can change the SVG properties on hover. For example change color to the part of the SVG image in our case fill property.

If we use the same list element then we can add a :hover pseudo-class with a slight change to the color. Newly encoded SVG will contain the code with an updated color (the inner circle is going to have a color of tomato).

li:hover {
  list-style-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' version='1.1' x='0px' y='0px' viewBox='0 0 426.667 426.667' style='enable-background:new 0 0 426.667 426.667;' xml:space='preserve'%3E%3Cg%3E%3Cg%3E%3Cg%3E%3Cpath d='M213.333,106.667c-58.88,0-106.667,47.787-106.667,106.667S154.453,320,213.333,320S320,272.213,320,213.333 S272.213,106.667,213.333,106.667z' fill='tomato'/%3E%3Cpath d='M213.333,0C95.467,0,0,95.467,0,213.333s95.467,213.333,213.333,213.333S426.667,331.2,426.667,213.333 S331.2,0,213.333,0z M213.333,384c-94.293,0-170.667-76.373-170.667-170.667S119.04,42.667,213.333,42.667 S384,119.04,384,213.333S307.627,384,213.333,384z' fill='gold'/%3E%3C/g%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}

Inputs and select element

To add custom styling to a select tag, you can hide the native arrow and add a custom one using an encoded SVG image:

select {
  -moz-appearance: none;
  -webkit-appearance: none;
  appearance: none;
  
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='292.4' height='292.4'%3E%3Cpath fill='%23333' d='M287 69.4a17.6 17.6 0 0 0-13-5.4H18.4c-5 0-9.3 1.8-12.9 5.4A17.6 17.6 0 0 0 0 82.2c0 5 1.8 9.3 5.4 12.9l128 127.9c3.6 3.6 7.8 5.4 12.8 5.4s9.2-1.8 12.8-5.4L287 95c3.5-3.5 5.4-7.8 5.4-12.8 0-5-1.9-9.2-5.5-12.8z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 8px center;
  background-size: 9px;
}
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