Fixes widget title alignment, content padding

[ryanml]

Fixes brave/brave-browser#9403

left/right padding was increased from 15px -> 20px, some other css adjustments had to be made to compensate

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Android
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that all lint errors/warnings are resolved (npm run lint)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

Defined in issue.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[emerick]

LGTM

[ryanml]

All pipeline steps pass, failure is due to unrelated browser test:

15:34:03  [  FAILED  ] BraveRewardsBrowserTest.PanelShowsCorrectPublisherData, where TypeParam =  and GetParam() =  (5745 ms)
15:34:03  [548/549] BraveRewardsBrowserTest.PanelShowsCorrectPublisherData (6026 ms)
15:34:07  [549/549] BraveRewardsBrowserTest.ProcessPendingContributions (4977 ms)
15:34:07  1 test failed:
15:34:07      BraveRewardsBrowserTest.PanelShowsCorrectPublisherData (../../brave/components/brave_rewards/browser/rewards_service_browsertest.cc:1713)
15:34:07  null
15:34:07  null