1. Check the mod-rewrite whether it is enabled or not by running the following command:

sudo a2enmod rewrite

You will get a message like this “This module is already enabled!” if your mod-rewrite is already enabled. If mod-rewrite is not enabled, follow the on-screen instructions to install it.

2. Open and edit the default file from this directory /etc/apache2/sites-available/default by using the following command:

sudo nano /etc/apache2/sites-available/default

if you don’t know how to use nano, than you may use another way to set the write permission by running the following command though it’s not recommended

sudo chmod -R 755 /etc/apache2/sites-available/default

3. Find the following Directory structure:

<Directory /var/www/>
Options Indexes FollowSymLinks MultiViews
AllowOverride None
Order allow,deny
allow from all
</Directory>

4. Find AllowOverride None and replace with the following text

AllowOverride All

5.Restart apache using:

sudo /etc/init.d/apache2 force-reload

And you are done!
Now you should now be able to view http://localhost/ with the correct css formatting for the cake default page.