How I can replace a CSS file for the scifi stack exchange site http://scifi.stackexchange.com/ with the CSS of this site http://diy.stackexchange.com/ as its blue color comforts my eye. Is there any chrome extension or work around to achieve this?
While Stylish relies on userstyles for custom styles, Stylebot has a an inbuilt sharing tool for share and fetch custom style sheets for most sites.
For this specific Stack Exchange, there's a userscript which allows you to swap stylesheets for any Stack Exchange site from any Stack Exchange site.
Note that the stylesheets are swapped after the page has loaded, so there will be a momentary flash where the original stylesheet is shown and then the new one is swapped. If you have a fast enough connection, this will probably be not noted by you.
Finally, recent Chrome update allows you to install userscripts & extensions via 1 click only from the Chrome WebStore.
To install the above linked userscript, you'll have to download/save the