css: make it possible and nice-looking to use <p> inside <li> and <td>.

css: make it possible and nice-looking to use <p> inside <li> and <td>.

Paragraphs inside list items and table cells are neither justified nor
indented, because it's often undesirable in such constrained spaces.
Also, in case of <li>, the padding after block elements is not removed
in order to have the spacing consistent.