<h2>❼</h2>
<div class=patterns id="seventh"><span hidden class=msg>If there's no pattern, try Firefox, the current browser doesn't support CSS element()</span></div>
<div id=snake >🐍</div>
#seventh {
	background: -moz-element(#snake), linear-gradient(45deg, transparent 20px, blue 20px, blue 30px, transparent 30px) white;
	background-size: 60px 60px;
	background-color: white;
}

#snake {
	color: transparent;
	text-shadow: 0 0 lime, 1px 1px white;
	width: 30px;
	height: 30px; 
	mix-blend-mode: multiply;
}

.patterns {
	width: 300px; height: 300px;
	margin: auto; border: 40px white solid;
}

body { background: black; font-family: 'crimson text';}

h2 { margin: auto; margin-top: 60px; width: 370px; text-align: right; background: yellow; padding-right: 10px;  }

.msg {margin-top: 120px; text-align: center; }

@supports not ((background: element(#snake)) or (background: -moz-element(#snake))){
	#seventh .msg {display: block;}
}

External CSS

  1. https://fonts.googleapis.com/css2?family=Crimson+Text&amp;display=swap

External JavaScript

This Pen doesn't use any external JavaScript resources.