org-html-head-include-default-style

org-html-head-include-default-style is a variable defined in `ox-html.el'.
Its value is

t

• This variable is safe as a file local variable if its value
  satisfies the predicate `booleanp'.

Documentation:
Non-nil means include the default style in exported HTML files.
The actual style is defined in `org-html-style-default' and
should not be modified. Use `org-html-head' to use your own
style information.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.