normalize.css: Incorporate useful changes from modern-normalize

We went from modern normalize to normalize.css, because I feel that the latter is bigger and better maintained.

Maybe we will switch in the future again, or make our own...

See (fonts): sindresorhus/modern-normalize#16

and (tab-size): sindresorhus/modern-normalize#17

Thanks modern-normalize!

src/normalize.css

@@ -1,5 +1,32 @@
 @import 'normalize.css';
 
+:root {
+	-moz-tab-size: 4;
+	tab-size: 4;
+}
+
 *, *::before, *::after {
   box-sizing: border-box;
 }
+
+body {
+  font-family:
+    -apple-system,
+    BlinkMacSystemFont,
+    'Segoe UI',
+    Roboto,
+    Helvetica,
+    Arial,
+    sans-serif,
+    'Apple Color Emoji',
+    'Segoe UI Emoji',
+    'Segoe UI Symbol';
+}
+
+code,
+kbd,
+samp,
+pre {
+  font-family: SFMono-Regular, Consolas, 'Liberation Mono', Menlo, Courier, monospace;
+  font-size: 1em;
+}