#78 refactor: update CSS styles to use design system

[twhite313]

Please always provide the GitHub issue(s) your PR is for, as well as test URLs where your change can be observed (before and after):

Fix #78

Test URLs:

• Original: https://www.esri.com/en-us/about/about-esri/overview
• Before: https://main--esri--aemsites.hlx.page/en-us/about/about-esri/overview
• After: https://style-update--esri--aemsites.hlx.page/en-us/about/about-esri/overview

[aem-code-sync[bot]]

Hello, I'm the AEM Code Sync Bot and I will run some actions to deploy your branch and validate page speed. In case there are problems, just click a checkbox below to rerun the respective action.

• [ ] Re-run PSI checks
• [ ] Re-sync branch

Commits

* [2d8a098](https://github.com/aemsites/esri/commit/2d8a0987f4bfba24c2a0021da7c68aebd1a3f234) :white_check_mark: (latest) * [871ea84](https://github.com/aemsites/esri/commit/871ea846aad01d5c8e61feb94849941073233d34) :white_check_mark: * [55ff770](https://github.com/aemsites/esri/commit/55ff770c3d79961c3e79122955c2663d57bac78e) :white_check_mark: * [449639e](https://github.com/aemsites/esri/commit/449639ed9fe8a3e4cefefc19a67b8906ab1502d6) :white_check_mark: * [2944a7e](https://github.com/aemsites/esri/commit/2944a7e1c4712fb11f37b215a84071f2b4216bec) :white_check_mark:

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/en-us/about/about-esri/overview

[twhite313]

@alexcarol this should be ready to review. Not sure why it keeps failing the PSI checked. All this is is an update to one css file.