Defining CSS media queries within selectors

Question

Are there any issues (performance is my primary concern) if instead of defining css selectors within media queries (example 1), you define media queries within css selectors (ex

Answer 1

There shouldn't be a performance difference looking at the way browsers handle media queries. Browser engines do serialize and strip out duplicated media-queries so they only need to evaluate each media query once. Also they cache the queries so that they can re-use it later on. It doesn’t matter if you use one big or multiple media-queries in your code assuming your values are mostly the same.

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Some of the possibilities when there can be performance issues

• You use multiple media queries with different values and the browser window is re-sized. As the browser window is re-sized, multiple media queries can be a big overhead on the cpu.
• When the CSS selectors are too complex. A complex CSS selector is much performance hindering than multiple media queries. So having multiple media queries inside complex selectors can cause performance issues