[html] Indent List in HTML and CSS

You can use [Adjacent sibling combinators] as described in the W3 CSS Selectors Recommendation1 So you can use a + sign (or even a ~ tilde) apply a padding to the nested ul tag, as you described in your question and you'll get the result you need. I also think what you want it to override the main css, locally. You can do this:

<style>
    li+ul {padding-left: 20px;}
</style>

This way the inner ul will be nested including the bullets of the li elements. I wish this was helpful! =)