Update normalize.css to v8.0.1

Normalize 8.0.0 regressed behavior in IE incorrectly rendering `main` tags. Applying normalize.css 8.0.1 rules to `preflight.css`

Author: markpinero

css/preflight.css

@@ -1,4 +1,4 @@
-/*! normalize.css v8.0.0 | MIT License | github.com/necolas/normalize.css */
+/*! normalize.css v8.0.1 | MIT License | github.com/necolas/normalize.css */
 
 /* Document
    ========================================================================== */
@@ -24,6 +24,14 @@ body {
   margin: 0;
 }
 
+/**
+ * Render the `main` element consistently in IE.
+ */
+
+main {
+  display: block;
+}
+
 /**
  * Correct the font size and margin on `h1` elements within `section` and
  * `article` contexts in Chrome, Firefox, and Safari.