div {
  background: url(https://example.com/image.png);
  background: url(https://example.com/image.png);
  background: url(https://example.com/image.png);
  background: url("https://example.com/image.png");
  background: url('https://example.com/image.png');
  background: URL('https://example.com/image.png');
  background: URL('https://example.com/image.png');
  background: url(data:image/png;base64,iRxVB0);
  background: url(#IDofSVGpath);
  background: url("//aa.com/img.svg" prefetch);
  background: url("//aa.com/img.svg" foo bar baz func(test));
  background: url("http://example.com/image.svg" param(--color var(--primary-color)));
  background: url();
  background: url("");
  background: url('');
  --foo: "http://www.example.com/pinkish.gif";
  background: src("http://www.example.com/pinkish.gif");
  background: SRC("http://www.example.com/pinkish.gif");
  background: src(var(--foo));
  background: url(https://example.com/image.png);
  background: url(https://example.com/image.png);
  background: url(https://example.com/image.png);
  background: url(https://example.com/image.png);
  background: url(image.png힙);
}
div {
  background: url(foo.img) red;
}
* {
  background: url('foo');
  background: url('f o');
  background: url('f  o');
  background: url('foo)');
  background: url('(foo');
  background: url('(foo)');
  background: url('\"foo\"');
}
.bar {
  background: url(http://example.com/image.svg param(--color var(--primary-color)));
}
.baz {
  background: url("http://example.com/image.svg" param(--color var(--primary-color)));
}
.foo {
  background: url(__ident__);
}
.foo {
  background: url(foo bar);
}
.bar {
  background: url(foo\\\\bar);
  background: url("foo\\\\bar");
}
