How can the appearance of the play button in the Webflow video module be customized to have a circle background instead of the default Vimeo rectangle shape?

To customize the appearance of the play button in the Webflow video module to have a circle background, you'll need to use custom code and CSS. Here's a step-by-step guide:

1. Add a Webflow video module to your project and select the Vimeo video you want to customize.
2. Give the video module a unique class name by selecting the video and going to the Style panel on the right-hand side.
3. In the Selector field, add a class name like `custom-video` (you can use any name you prefer).
4. Open the Custom code tab in the project settings or on the page settings where the video module is located.
5. In the Head Code section, add the following CSS code:

```css
.custom-video .w-lightbox-play-button {
position: relative;
width: 60px;
height: 60px;
background: #000;
border-radius: 50%;
}

.custom-video .w-lightbox-play-button:before {
content: '';
position: absolute;
left: 13px;
top: 17px;
width: 0;
height: 0;
border-style: solid;
border-width: 10px 0 10px 20px;
border-color: transparent transparent transparent rgba(255, 255, 255, 0.85);
}

.custom-video .w-lightbox-play-button:after {
content: '';
position: absolute;
left: 35px;
top: 15px;
width: 0;
height: 0;
border-style: solid;
border-width: 10px 0 10px 20px;
border-color: transparent transparent transparent rgba(255, 255, 255, 0.85);
}
```

6. Save the changes and preview your website to see the updated play button.

This CSS code targets the specific class `.w-lightbox-play-button` within the video module and customizes its appearance. The `width` and `height` properties set the dimensions of the circle background, while `background` defines the color of the circle (in this case, `#000` represents black). The `border-radius` property creates the circular shape by setting it to `50%`.

The `:before` and `:after` pseudo-elements are used to create the triangle within the circle. You can tweak the `left` and `top` properties to adjust the position of the triangle as needed.

Feel free to customize the CSS code further based on your design preferences or adjust the color, size, or position of the play button to fit your specific needs.