Migrate CSS files to subdirectory

_layouts/default.html

@@ -10,7 +10,7 @@
     <link rel="apple-touch-icon" sizes="180x180" href="/assets/apple-touch-icon.png" />
     <meta name="apple-mobile-web-app-title" content="Brendan Chen" />
     <link rel="manifest" href="/assets/site.webmanifest" />
-    <link rel="stylesheet" href="/assets/global.css">
+    <link rel="stylesheet" href="/assets/css/global.css">
 
 
     <title>{{ page.title }}</title>

_layouts/post.html

@@ -2,7 +2,7 @@
 layout: default
 ---
 
-<link rel="stylesheet" href="/assets/blog.css">
+<link rel="stylesheet" href="/assets/css/blog.css">
 
 <div class="infobar">
     <a href="/blog">All posts</a>