---
id: 5d822fd413a79914d39e98f2
title: Step 42
challengeType: 0
dashedName: step-42
---
# --description--
Add the new `bb1-window` class to the `.bb1a`, `.bb1b`, and `.bb1c` elements. This will apply the gradient to them.
# --hints--
You should not remove the `bb1a` class.
```js
assert.exists(document.querySelector('div.bb1a'));
```
You should add the `bb1-window` class to the `.bb1a` element.
```js
assert.exists(document.querySelector('div.bb1a.bb1-window'));
```
You should not remove the `bb1b` class.
```js
assert.exists(document.querySelector('div.bb1b'));
```
You should add the `bb1-window` class to the `.bb1b` element.
```js
assert.exists(document.querySelector('div.bb1b.bb1-window'));
```
You should not remove the `bb1c` class.
```js
assert.exists(document.querySelector('div.bb1c'));
```
You should add the `bb1-window` class to the `.bb1c` element.
```js
assert.exists(document.querySelector('div.bb1c.bb1-window'));
```
You should not change the `.bb1d` element.
```js
assert.exists(document.querySelector('div.bb1d'));
assert.notExists(document.querySelector('div.bb1d.bb1-window'));
```
# --seed--
## --seed-contents--
```html