Yes it should work - this is regular CSS. Add url / example.
“adjacent” means “immediately following”.
W3Schools Tryit Editor
immediately - so check again if in your site tree #div1 is after #div2 "immediately "
Good
<div id="div1"></div>
<div id="div2"></div>
“bad”
<div id="div1"></div>
<p>now #div2 not immediately after #div1</p>
<div id="div2"></div>
“bad2”
<div id="div1">
<div id="div2">i am child not sibling</div>
</div>