A "just add water" WordPress plugin in which you can manage column sizes with shortcodes It is a 10, 12 and 16 columns Grid System
[6_of_12]
{{content}}
[/6_of_12]
/* If you want to use 6 columns in the 12 columns grid system */
[12_of_16]
{{content}}
[/col_12_of_16]
/* If you want to use 12 columns in the 16 columns grid system */
/* Pattern */
[{n}_of_{x}]
{{content}}
[/{n}_of_{x}]
/*
{n} being the column size from 1 to {x}
{x} being the amount of columns for each line (10, 12 or 16)
{{content}} could be whatever you want to show inside the column element
*/
SC GridSystem - You can download from the WordPress Plugin Repository