<div class="container">
<div class="no">no</div>
<div>yes</div>
</div>
.container {
opacity: .5;
}
.no {
opacity: 1;
}
<div class="container">
<div class="no">no</div>
<div>yes</div>
</div>
.container div:not(.no) {
opacity: .5;
}
.no {
opacity: 1;
}