Question: Looking for a css selector for custom elements. 

```
<myApp-thing1></myApp-thing1>
<myApp-thing2></myApp-thing2>
<myApp-thing3></myApp-thing3>

```

I want to apply a css class to any element that starts with `<myApp-...>`. Is this possible?

Answer: 
No, there's not. Only the attribute selector can do this. The name of the attribute doesn't matter.

```
[class^="value"] 

```

This hits:

```
<div class="value-a"></div>
<div class="value-b"></div>
<div class="value-c"></div>

```

<https://developer.mozilla.org/en-US/docs/Web/CSS/Attribute_selectors>
What you're suggesting isn't possible, however, what **IS** possible is this:

```
<div myApp="thing1">

```

Then in CSS you can do this:

```
div[myApp] {
    background-color:pink;
}

```

You can even target a specific `<div>` with the `myApp` attribute by doing this in CSS:

```
div[myApp="thing1"] {
    background-color:red;
}

```

Hope this helps!