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<!DOCTYPE html> <html> <head> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style> /* 针对宽度小于 400 像素的设备： */ body { background-repeat: no-repeat; background-image: url('/i/photo/tulip_peach_blossom_s.jpg'); } /* 针对宽度大于等于 400 像素的设备： */ @media only screen and (min-device-width: 400px) { body { background-image: url('/i/photo/flower-5.jpg'); } } </style> </head> <body> </body> </html>