How is the size of popup windows set to fixed?

To set the size of popup windows to fixed, the resizable property of the page being used must be set to "No". When this property is disabled, it prevents users from adjusting the size of the popup window, resulting in a fixed size. This is particularly useful for maintaining the intended layout and user experience, as a fixed-size window ensures that content is displayed exactly as designed without the risk of distortion caused by resizing.

Other options may suggest methods to influence the popup's appearance or behavior, but they do not effectively establish a fixed size. For example, enabling a fixed-size option suggests an additional setting that may not be directly available in all contexts, while defining the size in popup settings might suggest specification but does not inherently prevent resizing by the user. CSS styling rules can control visuals and layout but are not typically employed to enforce the actual behavior of the window size. Thus, setting the resizable property to "No" is the definitive way to establish a fixed size for popup windows.