As you know, a new nine-column 960 grid system (http://960.gs) was implemented in the new Prestashop 1.5 theme version. Every column is 91px wide. Standard left and right indent for each column is 10 px., or 20 px. in total. grid_prestashop.css is a new grid system stylesheet file that appeared in the “css” directory. For its further use, it is just necessary to specify certain classes for columns (grid_1, grid_2, …). Currently, these classes are mostly used in the main files of the theme (header.tpl и footer.tpl).
In other Prestashop 1.5 theme files, each column width is assigned separately and regardless of the embedded grid. It means that there is no need for a designer to follow the rules of the system that is not quite flexible due to big width of a column. And it won’t be very difficult for theme developer to implement any design by deleting the classes from the abovementioned files. For full code purity, it is just required to delete importing the unnecessary @import url(“grid_prestashop.css”) file from global.css file.
In Prestashop 1.4, the theme stylesheet files were divided from global.css file into 19 dedicated css files plus css module files that are connected as and when necessary, depending on a page loaded. In Prestashop 1.5 css files of module files from “css/modules” directories were distributed immediately among the module directories. To optimize theme loading, it is recommended to set a “Use CCC for CSS” option.
This option will collect the contents of all the CSS theme files in one file, and will connect it only when loading a page. This will allow reducing a quantity of requests to the server, and, accordingly, accelerating loading the shop pages. This option is in section “Preferences:Performance” . To facilitate the process of theme updating in future until a new version, a separate style file can be created, and all the styles related to the theme can be stored in this file.