OpenStack Horizon How to include custom stylesheets css less

Method 1 (Tested with OpenStack Havana)
=========================== 

1)
Create a folder for css/less. like,
horizon/openstack_dashboard/static/custom_dashboard/less

2)
Goto that folder and create a css/less file dashboard.less
#cd horizon/openstack_dashboard/static/custom_dashboard/less
#vim dashboard.less

3)
Open  _stylesheets.html file and include your stylesheet there.
horizon/openstack_dashboard/templates/_stylesheets.html

{% load compress %}

{% compress css %}
link href='{{ STATIC_URL }}dashboard/less/horizon.less' type='text/less' media='screen' rel='stylesheet' />
link href='{{ STATIC_URL }}dashboard/less/rickshaw.css' type='text/css' media='screen' rel='stylesheet' />
link href='{{ STATIC_URL }}dashboard/less/horizon_charts.less' type='text/less' media='screen' rel='stylesheet' />
link href='{{ STATIC_URL }}custom_dashboard/less/dashboard.less' type='text/less' media='screen' rel='stylesheet' />
{% endcompress %}

link rel="shortcut icon" href="{{ STATIC_URL }}dashboard/img/favicon.ico"/>

4)
Restart apache
#sudo service apache2 restart

Notes:
----------
* In horizon you can find two  _stylesheets.html files
a)
horizon/openstack_dashboard/templates/_stylesheets.html
Included in  horizon/horizon/templates/base.html
Here,  base.html is the  base of all dashboard pages.

b)
horizon/horizon/templates/_stylesheets.html
Included in  horizon/horizon/templates/splash.html
Here,  splash.html is the Login Page.


Method 2 (Tested with OpenStack Havana)
=========================== 

1)
Create a folder for css/less. like,
horizon/openstack_dashboard/static/custom_dashboard/less

2)
Goto that folder and create a css/less file dashboard.less
#cd horizon/openstack_dashboard/static/custom_dashboard/less
#vim dashboard.less

3)
a)
Goto horizon/horizon/templates
#cd horizon/horizon/templates

b)
Rename  "base.html" to  "horizon_base.html"

c)
Create a new html file named  "base.html" and add following lines.
{% extends 'horizon_base.html' %}

{% block css %}
  {% include "_stylesheets.html" %}

  {% load compress %}
  {% compress css %}
  link href='{{ STATIC_URL }}custom_dashboard/less/dashboard.less' type='text/less' media='screen' rel='stylesheet' />
  {% endcompress %}
{% endblock %}

4)
Restart apache
#sudo service apache2 restart

Notes:
--------- 
a)
If you are planning to implement like following link, then you have to edit all dashboard templates
http://docs.openstack.org/developer/horizon/topics/customizing.html

b)
You can also try following method (recomended)
http://docs.openstack.org/grizzly/openstack-compute/install/yum/content/dashboard-custom-brand.html