As you can judge from the page below, the vertical space between the text and the header line and the text and the footer line is not equal.....
This is much more prominent in a PDF reader so I am trying to get equal space. How do I accomplish this using these settings?
\documentclass[12pt,a4paper,english,openany,oneside]{scrbook}
\usepackage[T1]{fontenc}
\usepackage[latin9]{inputenc}
\setcounter{secnumdepth}{-2}
\setcounter{tocdepth}{1}
\makeatletter
\pdfpageheight\paperheight
\pdfpagewidth\paperwidth
\usepackage{lmodern}
\usepackage[T1]{fontenc}
\usepackage[includeheadfoot,margin=1.5cm]{geometry}
\usepackage{etoolbox}
\usepackage{calc}
\makeatletter
\pretocmd{\@part}{\gdef\parttitle{#1}}{}{}
\pretocmd{\@spart}{\gdef\parttitle{#1}}{}{}
\makeatother
\usepackage{lipsum}
\usepackage[Bjornstrup]{fncychap}
\usepackage[nouppercase,headsepline,footsepline,automark]{scrpage2}
\clearscrheadfoot
\clearscrheadings
\chead{}
\cfoot{}
\ihead{headertext}
\ohead{\parttitle}
\ifoot{\rule{0pt}{\ht\strutbox+\dp\strutbox}\leftmark}
\ofoot{\rule{0pt}{\ht\strutbox+\dp\strutbox}\thepage}
\pagestyle{scrheadings}
\usepackage{url}
\usepackage{pdfcolmk}
\usepackage{graphicx}
\usepackage{tikz}
\providecommand{\HUGE}{\Huge}% if not using memoir
\newlength{\drop}% for my convenience
\makeatother
\usepackage{hyperref}