create stylesheet and link to it

Created a simple stylesheet, linked to it, and removed body color
attributes defined there. This reduces repetition and separates
style and presentation.

doc/style.css

@@ -0,0 +1,16 @@
+html {
+	background: #692764;
+	color:      #F5A0D8;
+}
+
+a:link {
+	color: #8AAEE6;
+}
+
+a:visited {
+	color: #2B9DA4;
+}
+
+a:active {
+	color: #95F0DA;
+}