If I have something like this in my HTML

```
    <div id="top">
        <div class="txt">
            <span class="welcome">Welcome on my website</span>
            <span class="links"><a href="Home">Home</a></span>
        </div>
    </div>

```

How I can select the welcome class in my CSS.

I've tried #top.txt.welcome but doesn't work.
I've also tried #top.txt span.welcome.