angular-cli/docs/documentation/stories/global-styles.md

Global styles

The styles.css file allows users to add global styles and supports CSS imports.

If the project is created with the --style=sass option, this will be a .sass file instead, and the same applies to scss/less/styl.

You can add more global styles via the apps[0].styles property in .angular-cli.json. These will be loaded exactly as if you had added them in a <link> tag inside index.html.

"styles": [
  "styles.css",
  "more-styles.css",
],

You can also rename the output and lazy load it by using the object format:

"styles": [
  "styles.css",
  "more-styles.css",
  { "input": "lazy-style.scss", "lazy": true },
  { "input": "pre-rename-style.scss", "output": "renamed-style" },
],