The text discusses the customization of the Daily Prebuilt iframe's dimensions on window resize while maintaining a constant aspect ratio. The default behavior is to fill the available space, but this can lead to issues if the parent container changes size often or if it's not the desired dimensions. To overcome this, two solutions are presented: using pure CSS with the `aspect-ratio` property and using plain JavaScript to set a resize event handler. Additionally, a React equivalent solution is provided for those who prefer working with React. The examples demonstrate how to achieve responsive video call dimensions while maintaining an aspect ratio, ensuring a seamless user experience.