fix: sidebar

[mariana-caetano]

Description

This PR fixes sidebar styling issues affecting navigation on smaller screens.

Now, the sidebar stays open regardless of screen size, and users can close it whenever they want. The solution aligns with the issue raised by the design team: vtexdocs/helpcenter#365

Types of changes

• 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 change)
• Requires change to documentation, which has been updated accordingly.

[github-actions]

This pull request does not contain a valid label. Please add one of the following labels: ['release-no', 'release-auto', 'release-patch', 'release-minor', 'release-major']