
作用:窗口大小决定css样式
/*手机*/@media (max-width: 768px){.media1{width:400px;}}/*平板*/@media (min-width: 768px) and (max-width: 979px){.media1{width:400px;}}/*PC*/@media (min-width: 979px){.media1{width:400px;}}
<style>/*手机*/@media screen and (max-width:600px){.box_2 {padding-top: 45px;}}/*平板*/@media screen and (min-width:600px) and (max-width:960px){.box_2 {padding-top: 45px;}}/*PC*/@media screen and (min-width:960px){.box_2 {padding-top: 45px;}}</style>