There are different options that can be set in cavendish/config.php

$cavendishLogoURL
Link to the Logo that should be displayed in the header

$cavendishLogoWidth
width of the logo as a number in px
 
$cavendishLogoHeight
height of the logo as a number in px
 
$cavendishLogoMargin
offset on top of the logo
 
$cavendishSiteWith
fixed width of the content area, if not set it's dynamic (default is false, that means dynamic)

$cavendishExtensionCSS
set this to false if you do not want to use Cavendish CSS for Extensions (default is true)

$cavendishQRCode
adding QR-Code to printpage (default is true)

$cavendishQRurladd  
used to track campaign for entry through QR Code, default is for Piwik (default="?pk_campaign=qr-code")

$cavendishcolor
select color of the theme: blue, brown or green (default is blue)