第一步设置meta
<meta name="viewport" content="width=device-width, initial-scale=1">
第二步reponsive.css
/* Normal desktop :1200px. */
@media (min-width: 1200px) and (max-width: 1500px) {}
/* Normal desktop :992px. */
@media (min-width: 992px) and (max-width: 1199px) {}
/* Tablet desktop :768px. */
@media (min-width: 768px) and (max-width: 991px)
/* Large Mobile :600px. */
@media only screen and (min-width: 600px) and (max-width: 767px){}
/* small mobile :320px. */
@media only screen and (min-width: 320px) and (max-width: 599px){}