VOTE-937: style refinements on voter guides

[mlloydbixal]

Jira ticket

Insert a link to the Jira ticket (e.g VOTE-XXX).

Description

Refines styles for voter guide pages and adds image background to the headings

Deployment and testing

Pre-deploy

1. Insert any required steps to take before merging and running post-deploy.

Post-deploy

1. Insert any required steps to take before beginning test.

QA/Test

1. npm run build
2. compare voter guide pages to figma files and ticket notes

Checklist for the Developer

• A link to the JIRA ticket has been included above.
• No merge conflicts exist with the target branch.
• Automated tests have passed on this PR.
• A reviewer has been designated.
• Deployment and testing steps have been documented above, if applicable.

Checklist for the Peer Reviewers

• The file changes are relevant to the task objective.
• Code is readable and includes appropriate commenting.
• Code standards and best practices are followed.
• QA/Test steps were successfully completed, if applicable.
• Applicable logs are free of errors.