Adding drop shadow to text using CSS

I've found some examples of code that you can add to a sites CSS that will provide a drop shadow to text. An example is:

h3.a {color: white; text-shadow: black 0.1em 0.1em 0.2em}

I would like to make all the text including all heading and navigation have a small drop shadow because the text is white on a coloured background. Does anyone know if there is a simple way to do this or would I have to add specific instructions to add the shadow to each type of text in each section?

Thanks!