redesign mars theme a bit. Better border color for search-input for dark theme

app/assets/stylesheets/sections/header.scss

@@ -227,6 +227,7 @@ header {
       .search-input {
         background-color: #D2D5DA;
         background-color: rgba(255, 255, 255, 0.5);
+        border: 1px solid #AAA;
 
         &:focus {
           background-color: white;

app/assets/stylesheets/themes/ui_mars.scss

@@ -16,25 +16,16 @@
     @extend .header-dark;
     &.navbar-gitlab {
       .navbar-inner {
-        background: #474D57 url('bg-header.png') repeat-x bottom;
-        border-bottom: 1px solid #444;
-      }
-    }
-
-    .search {
-      .search-input {
-        border: 1px solid rgba(0, 0, 0, 0.7);
-        background-color: #D2D5DA;
-        background-color: rgba(255, 255, 255, 0.5);
-
-        &:focus {
-          background-color: white;
+        background: #474D57;
+        border-bottom: 1px solid #373D47;
+        .app_logo {
+          &:hover {
+            background-color: #373D47;
+          }
         }
       }
     }
-    .search-input::-webkit-input-placeholder {
-      color: #666;
-    }
+
     .separator {
       background: #31363E;
       border-left: 1px solid #666;