Dev/login design

[HenrikeW]

Related issue(s) and PR(s)

This PR closes #134 .

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Design

List of changes made

• the login page got a new design
• the information to use Redmine credentials was added together with a link to Redmine
• a config file for ste CSS linter "stylelint" was added to allow legacy color notations. This was needed to make the box shadow work without the linter complaining.
• the basic-button class was moved in the stylesheet so that other, more specific button classes that are defined later will override the styles from basic-button if two classes are used simultaneously.

Screenshot of the fix

Testing

• open urdr without being logged in and see the new styling
• try logging in with wrong credentials to see that the login error still works and looks nice.
• log in and make sure nothing has changed on the /report page. Pay special attention to the buttons.

Further comments

Definition of Done checklist

• I have made an effort making the commit history understandable
• I have performed a self-review of my own code and commented any hard-to-understand areas
• Tests and lint/format validations are passing
• My changes generate no new warnings

[jonandernovella]

Looking good! I added some accessibility suggestions.

[jonandernovella]

LGTM!