Change CSS style to theme using inspect element

Usually, when you see the source is index, it means that the stylesheet is “inline,” meaning the CSS is written directly to an inline stylesheet in the HTML and not in an external file. If you click on the index link, it should switch to the Sources pane and show the inline stylesheet in the HTML. Or, if you do a view source on the page, you should be able to scroll down and find the CSS in question.

That is very difficult to figure out, it would depend upon the theme that you are using. If you are really interested in finding out, you’ll have to search through your theme files. However, if you are trying to change the CSS, you don’t want to change theme files anyway. If the theme gets updated because of feature enhancements, bug fixes, or security patches, or if the theme has to be updated because of a change to the WordPress core, then your changes will be lost. Instead, either create a child theme or use a CSS plugin like Jetpack or Custom CSS Manager, and then write your own CSS rule to override the existing rule. That’s the way you would normally change the CSS. If you use Jetpack, then the custom CSS file that Jetpack creates usually comes after any inline stylesheet, so it’s easier to write an overriding CSS rule.

@sam – modifying theme files really isn’t a good way to go – as those changes will be lost when the theme is updated.