Your existing code should be suitable for desktop displays, as the media query "(min-device-width: 768px)" covers a wide range of devices such as tablets and desktops. However, it's important to note that some browsers may not fully support media queries, which can lead to inconsistencies in how your styles are displayed.
There are a few potential issues to consider:
Firstly, certain cellphones may categorize themselves as "handheld" instead of "screen," causing CSS rules specified for "only screen ..." to not apply. Using "only all ..." can help address this issue and ensure styles are applied correctly.
For optimal performance, consolidating all CSS and media queries into a single file is recommended. Having multiple CSS files, even if some are disabled by media queries, can result in unnecessary downloads and increased network bandwidth usage.
To account for devices that fall outside predefined categories, it's advisable to include a default/fallback CSS block in each web page. This allows for consistent styling across different devices, with additional CSS building upon or overriding the default styles as needed.
Lastly, variations in device pixel density and viewport configurations can impact how designs are rendered on smartphones and other devices. It's important to account for these factors in your logic and adjust viewport settings using meta statements for more reliable responsive layouts.