installation-instructions.md

@@ -205,7 +205,7 @@ The configure script will consult some shell environment variables that will aff
 
 Below are some examples of using the above to achieve some common installation goals.
 
-## Installing in a specific location (e.g. in a home directory)
+### Installing in a specific location (e.g. in a home directory)
 
 The library can be installed in non-standard locations. For example, the usual convention of installing local programs in the `.local` subdirectory of a user's home can be achieved by:
 
@@ -219,7 +219,7 @@ After the library has been installed, we need to make sure that the Python inter
 $ export PYTHONPATH="$PYTHONPATH:$HOME/.local/lib/python3.6/site-packages"
 ```
 
-### Dependencies installed in a nonstandard directory
+#### Dependencies installed in a nonstandard directory
 
 If any of the dependencies have been installed in a nonstandard directory, we need to pass this information to the `configure` script. Suppose again these have been installed in the `$HOME/.local` directory. In this case we need
 ```bash
@@ -228,7 +228,7 @@ $ make install
 ```
 (typically, in such cases we also want to install the library itself in the home directory; for this we need to combine with the options in the previous section.)
 
-### Installing in a [virtualenv](http://docs.python-guide.org/en/latest/dev/virtualenvs/)
+#### Installing in a [virtualenv](http://docs.python-guide.org/en/latest/dev/virtualenvs/)
 
 To install graph-tool in a virtualenv we need to activate it before running configure
 ```bash