fix content page styling, add 404 page

kit/img/teaser-box-arrow-brand-secondary.svg

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xml:space="preserve"
+   style="enable-background:new 0 0 52 37;"
+   viewBox="0 0 52 37"
+   y="0px"
+   x="0px"
+   id="Ebene_1"
+   version="1.1"><metadata
+   id="metadata833"><rdf:RDF><cc:Work
+       rdf:about=""><dc:format>image/svg+xml</dc:format><dc:type
+         rdf:resource="http://purl.org/dc/dcmitype/StillImage" /><dc:title></dc:title></cc:Work></rdf:RDF></metadata><defs
+   id="defs831" />
+<style
+   id="style825"
+   type="text/css">
+	.st0{fill-rule:evenodd;clip-rule:evenodd;fill:#404040;}
+</style>
+<path
+   style="fill:#00a4e4;fill-opacity:1"
+   d="M35,0.55c-0.7-0.72-1.86-0.74-2.58-0.04c-0.01,0.01-0.03,0.03-0.04,0.04  c-0.71,0.73-0.71,1.9,0,2.63l13.29,13.44H1.83c-1.02,0-1.84,0.83-1.84,1.85c0,0,0,0.01,0,0.01c-0.01,1.03,0.81,1.87,1.84,1.89h43.84  L32.38,33.78c-0.71,0.74-0.71,1.91,0,2.65c0.7,0.72,1.86,0.74,2.58,0.04c0.01-0.01,0.03-0.03,0.04-0.04l16.43-16.62  c0.72-0.71,0.73-1.87,0.02-2.6c-0.01-0.01-0.01-0.01-0.02-0.02L35,0.55z"
+   class="st0"
+   id="Form_503_Kopie_7" />
+</svg>