docs: simplify style for headers

Remove the 1px border underneath all headers and make them
use black text to simplify visual appearance
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

docs/generic.css

@@ -41,7 +41,6 @@ h1, h2, h3, h4, h5, h6 {
   margin: 0px;
   padding: 0px;
   margin-bottom: 0.25em;
-  border-bottom: 1px solid #aaa;
 }
 
 h1 {

docs/libvirt.css

-h1, h2, h3, h4, h5, h6 {
-    color: #3c857c;
-}
-
 #nav {
     position: absolute;
     top: 0px;
@@ -541,6 +537,7 @@ br.clear {
 #footer h3 {
     margin:0px;
     font-size: 1em;
+    color: rgb(60, 133, 124);
 }
 
 #footer ul {