Format online documentation

Main goal to be more readable. Specifically:

- Make pages look more paper-like by

    * having margins for the text to the "paper",

    * having margins for the "paper" to the borders of the screen, and

    * applying a maximum width for the "paper".

- Change fonts to the free fonts FreeSerif, FreeSans and Mononoki.

- Change to:

    * Serif in body text.

    * Sans-serif almost everywhere else.

  I did this as I think it is easier to read texts with serif in
  comparison to sans-serif, and since it looks better when switching to
  and from the math Computer Modern Roman used by MathJax which is of
  serif-type.

- Reduce size of headers as they were overwhelmingly large.

- Remove box around inline code. As the documentation is written as a
  text, code should only be considered as another font family, similar
  to how italic/oblique is used to emphasize things and how italic
  symbols are used in mathematics: It is simply another "mode" in the
  text.

- Insert spacing between items in the sidebar as they were too close to
  each other.

- Reduce size of term in description list.

NOTE:  Some things in the documentation should be changed in order to
look the best. One of these is to use monospace/inline code when
referring to a computer variable. Another thing is to use monospace for
C-files (*.c, *.h) in the headers. Optionally, one can also start using
monospace when referring to websites and emails; I need to think about
how to do this in practice first (there are multiple options).

doc/source/_static/default.css

@@ -13,8 +13,94 @@ ul .toctree-l1 {
 
 div.body {
     min-width: 450px;
-    max-width: 100%;
+    max-width: 900px;
+    padding: 5% 7% 5% 7%;
+    margin-left: auto;
+    margin-right: auto;
 }
 
 li p { margin: 0.2em; }
 
+
+
+@import url("importfonts.css");
+
+
+/*
+################################################################################
+# set fonts
+################################################################################
+*/
+
+/* set standard for everything else */
+div.body
+{
+    font-family: FreeSerif, serif;
+    font-size: 110%;
+}
+b
+{
+    font-family: FreeSerif, serif;
+    font-style: normal;
+    font-weight: bold;
+    font-size: 105%;
+}
+em
+{
+    font-family: FreeSerif, serif;
+    font-style: italic;
+    font-size: 105%;
+}
+pre
+{
+    font-family: Mononoki, monospace;
+    font-size: 87%;
+}
+kbd, code /* Code and inputs */
+{
+    background-color: rgba(0, 0, 0, 0); /* Transparent */
+    font-family: Mononoki, monospace;
+    font-size: 87%;
+    padding: 0px;
+}
+
+/* headings */
+h1, h2, h3, h4, h5, h6
+{
+    font-family: FreeSans, sans-serif;
+}
+h1 code
+{
+    font-family: Mononoki, monospace;
+    font-size: 92%;
+    font-weight: bold; /* Typeset C-files as bold in main header */
+}
+h2 code, h3 code, h4 code, h5 code, h6 code
+{
+    font-family: Mononoki, monospace;
+    font-size: 92%;
+    font-weight: normal; /* Don't make it bold in other headers*/
+}
+div.body h1 { font-size: 180%; }
+div.body h2 { font-size: 140%; }
+div.body h3 { font-size: 125%; }
+div.body h4 { font-size: 115%; }
+div.body h5 { font-size: 110%; }
+div.body h6 { font-size: 100%; }
+
+/* sidebar */
+.sphinxsidebarwrapper { font-size: 110%; }
+.sphinxsidebarwrapper li { margin: 3px 0; }
+
+/* toctree */
+div[class="toctree-wrapper compound"]
+{
+    font-family: FreeSans, sans-serif; font-size: 92%;
+}
+div[class="toctree-wrapper compound"] code
+{
+    font-family: Mononoki, monospace; font-size: 92%;
+}
+
+/* description lists */
+dt { font-size: 90%; }

doc/source/_static/importfonts.css

@@ -0,0 +1,55 @@
+@font-face 
+{
+    font-family: FreeSans;
+    src: url(fonts/FreeSans-small.woff);
+}
+
+/* These two should never be used in our typesetting */
+/* @font-face */ 
+/* { */
+/*     font-family: FreeSans; */
+/*     src: url(fonts/FreeSansBold-small.woff); */
+/*     font-weight: bold; */
+/* } */
+
+/* @font-face */ 
+/* { */
+/*     font-family: FreeSans; */
+/*     src: url(fonts/FreeSansOblique.woff); */
+/*     font-style: oblique; */
+/* } */
+
+@font-face 
+{
+    font-family: FreeSerif;
+    src: url(fonts/FreeSerif-small.woff);
+}
+
+@font-face 
+{
+    font-family: FreeSerif;
+    src: url(fonts/FreeSerifItalic-small.woff);
+    font-style: italic;
+}
+
+@font-face 
+{
+    font-family: FreeSerif;
+    src: url(fonts/FreeSerifBold-small.woff);
+    font-weight: bold;
+}
+
+/* Neither should this one */
+/* @font-face */ 
+/* { */
+/*     font-family: FreeSerif; */
+/*     src: url(fonts/FreeSerifBoldItalic-small.woff); */
+/*     font-style: italic; */
+/*     font-weight: bold; */
+/* } */
+
+@font-face 
+{
+    font-family: Mononoki;
+    src: url(fonts/mononoki-Regular.woff2);
+}