有这样的CSS框架吗？

这个工具做到了：Adapt.js(也看看Less)

使用Adapt.js你可以做这样的事情：

// Edit to suit your needs.
var ADAPT_CONFIG = {
  // Where is your CSS?
  path: 'assets/css/',// false = Only run once,when page first loads.
  // true = Change on window resize and page tilt.
  dynamic: true,// Optional callBACk... myCallBACk(i,width)
  callBACk: myCallBACk,// First range entry is the minimum.
  // Last range entry is the maximum.
  // Separate ranges by "to" keyword.
  range: [
    '0px    to 760px  = mobile.css','760px  to 980px  = 720.css','980px  to 1280px = 960.css','1280px to 1600px = 1200.css','1600px to 1920px = 1560.css','1940px to 2540px = 1920.css','2540px           = 2520.css'
  ]
};