style intro page, ignore artist tags in Tag.trending, set root page to explore/posts/intro

app/assets/stylesheets/specific/explore.css.scss

@@ -16,4 +16,10 @@ div#c-explore-posts {
     padding: 1em;
     margin-bottom: 2em;
   }
+
+  div#a-intro {
+    width: 60em;
+    margin: 0 auto;
+    text-align: center;
+  }
 }

app/models/tag.rb

@@ -141,7 +141,12 @@ class Tag < ActiveRecord::Base
           counts = counts.to_a.select {|x| x[1] > trending_count_limit}
           counts = counts.map do |tag_name, recent_count|
             tag = Tag.find_or_create_by_name(tag_name)
-            [tag_name, recent_count.to_f / tag.post_count.to_f]
+            if tag.category == Danbooru.config.tag_category_mapping["artist"]
+              # we're not interested in artists in the trending list
+              [tag_name, 0]
+            else
+              [tag_name, recent_count.to_f / tag.post_count.to_f]
+            end
           end
 
           counts.sort_by {|x| -x[1]}.slice(0, 25).map(&:first)

config/routes.rb

@@ -352,5 +352,5 @@ Danbooru::Application.routes.draw do
   match "/static/benchmark" => "static#benchmark"
   match "/static/name_change" => "static#name_change", :as => "name_change"
 
-  root :to => "posts#index"
+  root :to => "explore/posts#intro"
 end

test/functional/explore/posts_controller_test.rb

@@ -0,0 +1,27 @@
+require "test_helper"
+
+module Explore
+  class PostsControllerTest < ActionController::TestCase
+    context "in all cases" do
+      setup do
+        CurrentUser.user = FactoryGirl.create(:user)
+        CurrentUser.ip_addr = "127.0.0.1"
+        FactoryGirl.create(:post)
+      end
+
+      context "#popular" do
+        should "render" do
+          get :popular
+          assert_response :success
+        end
+      end
+
+      context "#intro" do
+        should "render" do
+          get :intro
+          assert_response :success
+        end
+      end
+    end
+  end
+end