问题
So far, I can only tell if a property is inherited or not, but I need to know the source of inheritance, (for ex, which CSS file caused the final value ?) is this possible ?
Is there a handy tool for this ?
EDIT
Here is what I get in chrome Computed Style (show inheritance) See the direction property, there is no info about its inheritance source

回答1:
You can do this job very easily by using Firebug in Firefox or Chrome's Developer Tools.
Chrome Developer Tools
Like image shows below.

For more information check Chrome Developer Tools: Element Styles Here
In Firebug
Like image shows below.

For more information check CSS Development Here
You can install Fire Bug From Here
Update 1:
You can find it by just clicking Show Inherited
check box on Chrome's computed style
panel likes below.

Update 2:
In Firebug, you just click inherited element what I showed below image.Then It will guide you to the relevant Inherited element's location.
P.S. - Same can do by using chrome Tool.

回答2:
The cascading nature of CSS makes the Styles browser in the Elements Tab very useful, you can see the individual styles and where they come from, you can also see the final set of styles after it is computed and applied to the element.

EDIT
You can refer a property and its source from computed style panel

Reference
- Chrome Dev Tools.
来源:https://stackoverflow.com/questions/14065400/how-to-detect-css-inheritance-source