last not .X

by DoubleYo

HTML

<div class="container">
    <div class="Y">plop</div>
    <div class="Y">plop</div>
    <div class="Y">plop</div>
    <div class="Y">plop</div>
    <div class="Y">plop</div> <!-- this I want to style -->
    <div class="X Y">plop</div>
</div>

<div class="container">
    <div class="Y">plop</div>
    <div class="Y">plop</div> <!-- this I want to style -->
    <div class="X Y">plop</div>
</div>

CSS

.container {
    margin: 10px;
    border: solid grey 1px;
}

.Y:nth-last-child(-n+3) + :not(.X) {
    color:red;
}