[EOSF-881] Fix contrast issue for error pages.

[adlius]

Purpose

Currently, the color contrast for support email link on ECSarxiv and EarthArxiv error pages are not enough. This PR fix the issue.

Summary of Changes

Change the component's CSS class to 'prerpint-header' and 'preprint-hearder-error'.
Added a style file to the component to add padding and bottom margin.

Side Effects / Testing Notes

The error page for OSF preprint would also be changed to using the background image on the landing page, which should be more consistent.

Ticket

https://openscience.atlassian.net/browse/EOSF-881

Reviewer Checklist

• meets requirements
• easy to understand
• DRY
• testable and includes test(s)
• changes described in CHANGELOG.md

[coveralls]

Coverage remained the same at 25.453% when pulling fd66612 on adlius:css-contrast into a03b964 on CenterForOpenScience:develop.

[jamescdavis]

Please describe this change in the [unreleased] section of CHANGELOG.md

[adlius]

CHANGELOG.md is modified.

[coveralls]

Coverage increased (+0.04%) to 25.489% when pulling 8dfc46d on adlius:css-contrast into a03b964 on CenterForOpenScience:develop.

[hmoco]

This looks good. One small concern, and this seems to be intended, but if so we should be more explicit about it. Replacing preprint-error-page does not allow brands to change their color here. The PR description implies that that is intended. However, preprint-error-page is still a class in the https://github.com/CenterForOpenScience/ember-osf-preprints/blob/develop/app/styles/brands/_brand.scss file. My opinion is that if we intend to remove that option, the class should also be removed from the customized .css brand files. Opinions? @jamescdavis @adlius

[adlius]

You're right. The side effect is that the brands cannot customize how they want the error page to look like without also changing the header elements. This should be more favorable as it results in more consistent looks. If that is the case, I can go and remove that from the CSS files for brands.

[hmoco]

I honestly prefer the button solution, to keep brands' themes consistent. However, that is inconsistent UI with our other support links, inconsistent UX to what buttons normally do versus anchor tags, and it might look ugly. Also, its not like all our brands have great themes (cough cough agrixiv). So, I'm happy with just removing the CSS pertinent to error pages from those files and the brand template.