HTML: The Markup Language  h4heading # T  The h1 through h6
elements are headings for the sections with which they are
associated.  Permitted content #  Permitted attributes #
Additional constraints and admonitions #  Tag omission #  An h4
element must have both a start tag and an end tag.  Permitted
parent elements #  any element that can contain flow elements,
hgroup  DOM interface #  interface HTMLHeadingElement :
HTMLElement {};  Typical default display properties #  h4 {
display: block; margin: 1.33em 0 1.33em 0; font-weight: bold; }