Emulating targeting a preceding sibling through :has()

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Guesstimate of what the code would look like 

.section {
	background: #eee;
	border-bottom: 1px solid #ddd;
	margin-bottom: 8px;
	padding: 8px;
}
.box {
	background: #fff;
	border: 1px solid rgba(0, 0, 0, .5);
	border-radius: 8px;
	margin-bottom: .5em;
	padding: 4px;
}

.section > .box:first-of-type:has(~ .box:nth-of-type(3)) {
	background: #0f0;
}
.section > .box:first-of-type:not(:has(~ .box:nth-of-type(3))) {
	background: #f00;
}

What's going on

This pen is intended to demonstrate how a developer could possibly target a preceding sibling using :has() .
If there is a third .box element ahead of the first .box element, the first .box would be shaded green.
If the CSS is unable to find a third .box sibling ahead of the first, it would be shaded red instead.

Emulating .section > .box:first-of-type:has(~ .box:nth-of-type(3))

Box 1
Box 2
Box 3

Emulating .section > .box:first-of-type:not(:has(~ .box:nth-of-type(3)))

Box 1
Box 2

References