cmd/compile: reduce the size of header in ssa.html

Big title and the help link were taking almost 15% of vertical space.
The CL makes header smaller.

Change-Id: I36f55ceb23b444e8060a479500c5f709cbd3f6f0
Reviewed-on: https://go-review.googlesource.com/c/144577Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

src/cmd/compile/internal/ssa/html.go

@@ -50,10 +50,14 @@ body {
     font-family: Arial, sans-serif;
 }
 
+h1 {
+    font-size: 18px;
+    display: inline-block;
+    margin: 0 1em .5em 0;
+}
+
 #helplink {
-    margin-bottom: 15px;
-    display: block;
-    margin-top: -15px;
+    display: inline-block;
 }
 
 #help {