To install it, open this page in your browser, and then drag the following link to your bookmark bar: SelectorGadget.
To use it, open the page
Click on the element you want to select. SelectorGadget will make a first guess at what css selector you want. It’s likely to be bad since it only has one example to learn from, but it’s a start. Elements that match the selector will be highlighted in yellow.
Click on elements that shouldn’t be selected. They will turn red. Click on elements that should be selected. They will turn green.
Iterate until only the elements you want are selected. SelectorGadget isn’t perfect and sometimes won’t be able to find a useful css selector. Sometimes