Fix sidebar by making navigation postion fixed

Closes: #184

Author: onur

templates/navigation_rustdoc.hbs

@@ -1,4 +1,4 @@
-    <div class="nav-container">
+    <div class="nav-container nav-container-rustdoc">
       <div class="container-rustdoc rustdoc-navigation">
         <div class="pure-menu pure-menu-horizontal">
           <form action="/releases/search" method="GET" class="landing-search-form-nav">

templates/style.scss

@@ -51,11 +51,14 @@ html, button, input, select, textarea,
 div.rustdoc {
     font-family: $font-family-serif;
     padding: 10px 15px 20px 15px;
-}
+    margin-top: 32px;
 
-.sidebar {
-    padding-top: 32px;
-    z-index: -1;
+    .sidebar {
+        padding-top: 32px;
+        .block > ul > li {
+            margin-right: -10px;
+        }
+    }
 }
 
 body {
@@ -103,13 +106,6 @@ div.container {
 div.container-rustdoc {
     max-width: 1200px;
     text-align: left;
-
-    #theme-picker {
-        margin-top: 30px;
-    }
-    #theme-choices {
-        top: 60px;
-    }
 }
 
 div.nav-container {
@@ -221,6 +217,14 @@ div.nav-container {
     }
 }
 
+div.nav-container-rustdoc {
+    position: fixed;
+    left: 0;
+    top: 0;
+    z-index: 999;
+    width: 100%;
+}
+
 div.landing {
     text-align: center;
     padding-top: 30px;