How do I use CSS to change the layout of my HTML page for different devices and screen sizes?
user
You can use CSS media queries to change the layout of your HTML page for different devices and screen sizes. Media queries allow you to specify different styles for different conditions, such as screen width, height, and orientation.

Here's an example of how to use a media query to change the layout of a web page for devices with a screen width of less than 600 pixels:

/* Styles for screens with a width of 600 pixels or more */
@media screen and (max-width: 600px) {
  /* Styles for screens with a width of less than 600 pixels */
  /* For example, you can make the font size smaller and adjust the layout */
  body {
    font-size: 14px;
  }
  .container {
    display: flex;
    flex-wrap: wrap;
  }
  .item {
    width: 50%;
  }
}

In the example above, we use the @media rule to define a media query for screens with a maximum width of 600 pixels. The styles within the curly braces apply only to screens that match this condition.

Within the media query, we can apply different styles to different HTML elements. In the example above, we adjust the font size of the body element and use CSS Flexbox to adjust the layout of a container and its child items. You can adjust the styles as per your requirement.

Media queries can be complex and may involve multiple conditions, but they are a powerful tool for creating responsive web designs that adapt to different devices and screen sizes.
assistant
Exactly what file do I write that in ? What do I call the file. And how will I link to it in the index.html file? and could you maybe generate an example of the files in their entirety for me so I get a better understanding of the topic?
user
The recommended method to include the above CSS media queries is to put it into a dedicated CSS file and import it into each of your HTML page.

Put the below CSS content into a file called `devices.css`.

    @media screen and (max-width: 600px) {
        body {
            font-size: 14px;
        }
        .container {
            display: flex;
            flex-wrap: wrap;
        }
        .item {
            width: 50%;
        }
    }

Then, inside the `<head>` element of your HTML file, add the following line:

    <link rel="stylesheet" href="devices.css">

You can change the name of `devices.css` to other names, but you must change the `link href` part accordingly.
assistant
Okay, as a next step i would like to add a function to my webpage. I would like to have a settings tab which has a section layout formats. There I would like to make the different screen size formats available for the user, s.t. it could switch manually between the layouts, if he wanted to. Is that possible? If yes, can you give me an example using the code snippets from above?
user