fix: minor style improvements

DocGen4/Output/Template.lean

@@ -48,8 +48,8 @@ def baseHtmlGenerator (title : String) (site : Array Html) : BaseHtmlM Html := d
           <p class="header_filename break_within">{title}</p>
           -- TODO: Replace this form with our own search
           <form action="https://google.com/search" method="get" id="search_form">
-            <input type="hidden" name="sitesearch" value="https://leanprover-community.github.io/mathlib_docs"/>
-            <input type="text" name="q" autocomplete="off"/>
+            <input type="hidden" name="sitesearch" value="https://leanprover-community.github.io/mathlib4_docs"/>
+            <input type="text" name="q" autocomplete="off"/>&#32;
             <button>Google site search</button>
           </form>
         </header>
@@ -57,7 +57,7 @@ def baseHtmlGenerator (title : String) (site : Array Html) : BaseHtmlM Html := d
         [site]
 
         <nav class="nav">
-          <iframe src={s!"{←getRoot}/navbar.html"} class="navframe" frameBorder="0"></iframe>
+          <iframe src={s!"{←getRoot}navbar.html"} class="navframe" frameBorder="0"></iframe>
         </nav>
       </body>
     </html>

static/style.css

@@ -262,6 +262,12 @@ nav {
     width: 100%;
 }
 
+.navframe .nav {
+    position: absolute;
+    left: 0;
+    margin-left: 0;
+}
+
 .internal_nav .imports {
     margin-bottom: 1rem;
 }