I changed the color of an element on the page by clicking on the button, how to save this change to the cache so that the style does not disappear when the page is refreshed?

Question

CodeIgniter

I changed the color of an element (for example, the header) on the page by clicking on the button, how can I save this change to the cache so that the style does not disappear when the page is refreshed? the Codeigniter framework, if that matters...