Before start learning about Flexible Grid System, you need knowledge about Grid System and Responsive Design.
Responsive Meta
  <meta name="viewport" content="width=device-width, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no">
Compiled View
By switching to compile view, you can examine the CSS properties of classes and mixins. Knowledge about this topic will help to improve your abilities.
On CSS; static section, on Sass, Less or Stylus, dynamic sections are marked as @variable.
For browser compatibility requirements -ms, -moz and -webkit aren't added to the samples.
Dynamic (Core)
Dynamic (Compilation Tool)
Sass Plus
Less Plus
Stylus Plus
Static (Compiled)
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