body {
  margin: 0;
  background: url('../a.jpg');
  border-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" x="0px" y="0px" viewBox="0 0 256 256"><g><g><polygon points="79.093,0 48.907,30.187 146.72,128 48.907,225.813 79.093,256 207.093,128"/></g></g></svg>');
}
p {
  color: red;
  background: url('./b.jpg');
}
body > p {
  color: yellow;
}