Delete normalize.css
Delete normalize.css.

- The need for CSS resets diminishes as IE11 support ends next year.
- normalize.css has stopped updating since last 3 years ago.
- The definition of normalize.css is the latest (final?) [8.0.1](https://necolas.github.io/normalize.css/8.0.1/normalize.css), which is quite small, so it should be okay to remove it.
