Determine whether it is a mobile screen or a computer screen, and then load a css file.

Determine whether the screen is a mobile phone screen or a computer screen, and then load a css file .. New users ask questions, such as questions, articles about this and so on. & nbsp; OK & nbsp; thank you! & Nbsp; 4-inch mobile phone screen or computer screen, and then load a css file ..
New users may ask questions, such as questions. if you have any articles in this area, please send them. thank you!
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I have determined a screen width, and a 4-inch screen cell phone with a size of> 1024a.css <00001024 B .css is okay... If you want note3 to be 5.7, the screen width will be 1080...