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　　iPhones

/* ----------- iPhone 4 and 4S ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 320px)   and (max-device-width: 480px)  and (-webkit-min-device-pixel-ratio: 2) {}/* Portrait */@media only screen   and (min-device-width: 320px)   and (max-device-width: 480px)  and (-webkit-min-device-pixel-ratio: 2)  and (orientation: portrait) {}/* Landscape */@media only screen   and (min-device-width: 320px)   and (max-device-width: 480px)  and (-webkit-min-device-pixel-ratio: 2)  and (orientation: landscape) {}/* ----------- iPhone 5 and 5S ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 320px)   and (max-device-width: 568px)  and (-webkit-min-device-pixel-ratio: 2) {}/* Portrait */@media only screen   and (min-device-width: 320px)   and (max-device-width: 568px)  and (-webkit-min-device-pixel-ratio: 2)  and (orientation: portrait) {}/* Landscape */@media only screen   and (min-device-width: 320px)   and (max-device-width: 568px)  and (-webkit-min-device-pixel-ratio: 2)  and (orientation: landscape) {}/* ----------- iPhone 6 ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 375px)   and (max-device-width: 667px)   and (-webkit-min-device-pixel-ratio: 2) { }/* Portrait */@media only screen   and (min-device-width: 375px)   and (max-device-width: 667px)   and (-webkit-min-device-pixel-ratio: 2)  and (orientation: portrait) { }/* Landscape */@media only screen   and (min-device-width: 375px)   and (max-device-width: 667px)   and (-webkit-min-device-pixel-ratio: 2)  and (orientation: landscape) { }/* ----------- iPhone 6+ ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 414px)   and (max-device-width: 736px)   and (-webkit-min-device-pixel-ratio: 3) { }/* Portrait */@media only screen   and (min-device-width: 414px)   and (max-device-width: 736px)   and (-webkit-min-device-pixel-ratio: 3)  and (orientation: portrait) { }/* Landscape */@media only screen   and (min-device-width: 414px)   and (max-device-width: 736px)   and (-webkit-min-device-pixel-ratio: 3)  and (orientation: landscape) { }

　　Galaxy Phones

/* ----------- Galaxy S3 ----------- *//* Portrait and Landscape */@media screen   and (device-width: 320px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 2) {}/* Portrait */@media screen   and (device-width: 320px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 2)   and (orientation: portrait) {}/* Landscape */@media screen   and (device-width: 320px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 2)   and (orientation: landscape) {}/* ----------- Galaxy S4 ----------- *//* Portrait and Landscape */@media screen   and (device-width: 320px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3) {}/* Portrait */@media screen   and (device-width: 320px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3)   and (orientation: portrait) {}/* Landscape */@media screen   and (device-width: 320px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3)   and (orientation: landscape) {}/* ----------- Galaxy S5 ----------- *//* Portrait and Landscape */@media screen   and (device-width: 360px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3) {}/* Portrait */@media screen   and (device-width: 360px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3)   and (orientation: portrait) {}/* Landscape */@media screen   and (device-width: 360px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3)   and (orientation: landscape) {}

　　HTC Phones

/* ----------- HTC One ----------- *//* Portrait and Landscape */@media screen   and (device-width: 360px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3) {}/* Portrait */@media screen   and (device-width: 360px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3)   and (orientation: portrait) {}/* Landscape */@media screen   and (device-width: 360px)   and (device-height: 640px)   and (-webkit-device-pixel-ratio: 3)   and (orientation: landscape) {}

　　Nexus Phones

/* ----------- Nexus 4 ----------- *//* Portrait and Landscape */@media screen   and (device-width: 384px)   and (device-height: 592px)   and (-webkit-device-pixel-ratio: 2) {}/* Portrait */@media screen   and (device-width: 384px)   and (device-height: 592px)   and (-webkit-device-pixel-ratio: 2)  and (orientation: portrait) {}/* Landscape */@media screen   and (device-width: 384px)   and (device-height: 592px)   and (-webkit-device-pixel-ratio: 2)  and (orientation: landscape) {}/* ----------- Nexus 5 ----------- *//* Portrait and Landscape */@media screen   and (device-width: 360px)   and (device-height: 592px)   and (-webkit-device-pixel-ratio: 3) {}/* Portrait */@media screen   and (device-width: 360px)   and (device-height: 592px)   and (-webkit-device-pixel-ratio: 3)  and (orientation: portrait) {}/* Landscape */@media screen   and (device-width: 360px)   and (device-height: 592px)   and (-webkit-device-pixel-ratio: 3)  and (orientation: landscape) {}

　　iPads

/* ----------- iPad mini ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (-webkit-min-device-pixel-ratio: 1) {}/* Portrait */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (orientation: portrait)   and (-webkit-min-device-pixel-ratio: 1) {}/* Landscape */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (orientation: landscape)   and (-webkit-min-device-pixel-ratio: 1) {}/* ----------- iPad 1 and 2 ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (-webkit-min-device-pixel-ratio: 1) {}/* Portrait */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (orientation: portrait)   and (-webkit-min-device-pixel-ratio: 1) {}/* Landscape */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (orientation: landscape)   and (-webkit-min-device-pixel-ratio: 1) {}/* ----------- iPad 3 and 4 ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (-webkit-min-device-pixel-ratio: 2) {}/* Portrait */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (orientation: portrait)   and (-webkit-min-device-pixel-ratio: 2) {}/* Landscape */@media only screen   and (min-device-width: 768px)   and (max-device-width: 1024px)   and (orientation: landscape)   and (-webkit-min-device-pixel-ratio: 2) {}

　　Galaxy Tablets

/* ----------- Galaxy Tab 10.1 ----------- *//* Portrait and Landscape */@media   (min-device-width: 800px)   and (max-device-width: 1280px) {}/* Portrait */@media   (max-device-width: 800px)   and (orientation: portrait) { }/* Landscape */@media   (max-device-width: 1280px)   and (orientation: landscape) { }

　　Nexus Tablets

/* ----------- Asus Nexus 7 ----------- *//* Portrait and Landscape */@media screen   and (device-width: 601px)   and (device-height: 906px)   and (-webkit-min-device-pixel-ratio: 1.331)   and (-webkit-max-device-pixel-ratio: 1.332) {}/* Portrait */@media screen   and (device-width: 601px)   and (device-height: 906px)   and (-webkit-min-device-pixel-ratio: 1.331)   and (-webkit-max-device-pixel-ratio: 1.332)   and (orientation: portrait) {}/* Landscape */@media screen   and (device-width: 601px)   and (device-height: 906px)   and (-webkit-min-device-pixel-ratio: 1.331)   and (-webkit-max-device-pixel-ratio: 1.332)   and (orientation: landscape) {}

　　Kindle Fire

/* ----------- Kindle Fire HD 7" ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 800px)   and (max-device-width: 1280px)   and (-webkit-min-device-pixel-ratio: 1.5) {}/* Portrait */@media only screen   and (min-device-width: 800px)   and (max-device-width: 1280px)   and (-webkit-min-device-pixel-ratio: 1.5)   and (orientation: portrait) {}/* Landscape */@media only screen   and (min-device-width: 800px)   and (max-device-width: 1280px)   and (-webkit-min-device-pixel-ratio: 1.5)   and (orientation: landscape) {}/* ----------- Kindle Fire HD 8.9" ----------- *//* Portrait and Landscape */@media only screen   and (min-device-width: 1200px)   and (max-device-width: 1600px)   and (-webkit-min-device-pixel-ratio: 1.5) {}/* Portrait */@media only screen   and (min-device-width: 1200px)   and (max-device-width: 1600px)   and (-webkit-min-device-pixel-ratio: 1.5)   and (orientation: portrait) {}/* Landscape */@media only screen   and (min-device-width: 1200px)   and (max-device-width: 1600px)   and (-webkit-min-device-pixel-ratio: 1.5)   and (orientation: landscape) {}

　　Laptops

/* ----------- Non-Retina Screens ----------- */@media screen   and (min-device-width: 1200px)   and (max-device-width: 1600px)   and (-webkit-min-device-pixel-ratio: 1) { }/* ----------- Retina Screens ----------- */@media screen   and (min-device-width: 1200px)   and (max-device-width: 1600px)   and (-webkit-min-device-pixel-ratio: 2)  and (min-resolution: 192dpi) { }

　　Apple Watch

/* ----------- Apple Watch ----------- */@media  (max-device-width: 42mm)  and (min-device-width: 38mm) { }

　　Moto 360 Watch

/* ----------- Moto 360 Watch ----------- */@media   (max-device-width: 218px)  and (max-device-height: 281px) { }

　　

浏览器缓存机制，其实主要就是HTTP协议定义的缓存机制（如： Expires； Cache-control等）。但是也有非HTTP协议定义的缓存机制，如使用HTML Meta 标签，Web开发者可以在HTML页面的节点中加入
    标签，代码如下：