You can control how (and if) elements display by using the display property. By using the display property you can set the following values:
inline | block | list-item | inline-block | table inline-table | table-row-group | table-header-group table-footer-group | table-row | table-column-group table-column | table-cell | table-caption | none | inherit
This allows you to display block-level elements as inline elements, while still giving you full control over box model properties. Try it with the heading 4s below.