查看demo

<style>
    p:last-child{
        background-color: #ccc;
    }
    div>:not(p){
        color: blue;
    }
    div p:not(:last-child){
        border: 1px solid #ccc;
    }
</style>

<div class="wrap">
    <h3>title</h3>
    <p>one</p>
    <p>two</p>
    <p>three</p>
</div>