optimize documentation layout

scripts/bootstrap.sh

@@ -968,6 +968,28 @@ to --condition AX_USE_DOXYGEN doc/style.css <<EOF
   padding: 1ex;
   margin: 0;
 }
+img, object {
+  max-width: 100% !important;
+}
+@media (max-width: 50em) {
+  #navrow1, #navrow2 {
+    display: block
+  }
+  #side-nav, #splitbar, .ui-resizable-handle ui-resizable-e, .ui-resizable-handle ui-resizable-s {
+    display: none;
+  }
+  #doc-content {
+    margin-left: 0 !important;
+  }
+}
+@media (min-width: 50em) {
+  #navrow1, #navrow2 {
+    display: none;
+  }
+  #side-nav, #splitbar, .ui-resizable-handle ui-resizable-e, .ui-resizable-handle ui-resizable-s {
+    display: block
+  }
+}
 EOF
 if testtag AX_USE_DOXYGEN; then
     copy doc/plantuml.jar
@@ -1047,7 +1069,7 @@ if testtag AX_USE_DOXYGEN; then
         doxyreplace HTML_FOOTER footer.html
         doxyreplace HTML_EXTRA_STYLESHEET style.css
         doxyreplace HTML_DYNAMIC_SECTIONS YES
-        doxyreplace DISABLE_INDEX YES
+        doxyreplace DISABLE_INDEX NO
         doxyreplace GENERATE_TREEVIEW YES 
         if testtag AX_BUILD_EXAMPLES; then
             doxyreplace EXAMPLE_PATH @top_srcdir@/examples