Add spacing around top-level header

Rather than squashing the "Raspberry Pi Documentation" header, search
bar and tab menu altogether, add some spacing between each element to be
more consistent with our other sites.

Author: mudge

jekyll-assets/css/style.css

@@ -134,13 +134,12 @@ code {
 
 .toptitle h1 {
   font-size: 2.5em;
-  font-weight: lighter;
-  letter-spacing: 1px;
+  font-weight: 300;
   color: var(--bg);
   position: relative;
   margin-top: 0px;
   text-align: center;
-  padding-top: 10px;
+  padding-top: 40px;
   margin-left: 10px;
   flex-grow: 1;
 }
@@ -215,7 +214,7 @@ div.subtitle p {
 
 #search-container {
   width: 50%;
-  margin: auto;
+  margin: 20px auto 0;
   max-width: 900px;
 }
 
@@ -1665,6 +1664,7 @@ div#tab-menu {
   width: 100%;
   height: 80px;
   margin-bottom: -28px;
+  margin-top: 20px;
 }
 
 ul#tab-container {