Make the title fonts consistent across different pages

[stevenjoezhang]

Proposed change

I've noticed that the structure of different panel pages in Home Assistant uses several different implementations. Some pages use the <div class="main-title"> element for their titles, while others use ha-top-app-bar-fixed (based on the Material Design's TopAppBarFixedBase). However, the former usually sets the title font size to 20px via CSS, while the latter does not, resulting in it being the default size. When switching between different panel pages, you can observe the jitter in the title font size. This pull request fixes this issue by adding several definitions for font-size.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io