## Description
- In the fixed layout system, the background of the canvas fell short of
the bottom most widget.
- This was due to an unnecessary `height: 100%` applied to the Fixed
layout system.
- Changed the code so that the `height: 100%` is only applied in the
Anvil layout system
#### PR fixes following issue(s)
Fixes#29797Fixes#29883
#### Type of change
- Bug fix (non-breaking change which fixes an issue)
## Testing
#### How Has This Been Tested?
- [x] Manual
- [ ] JUnit
- [ ] Jest
- [x] Cypress
#### Test Plan
#### Issues raised during DP testing
## Checklist:
#### Dev activity
- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] PR is being merged under a feature flag
#### QA activity:
- [ ] [Speedbreak
features](https://github.com/appsmithorg/TestSmith/wiki/Guidelines-for-test-plans#speedbreakers-)
have been covered
- [ ] Test plan covers all impacted features and [areas of
interest](https://github.com/appsmithorg/TestSmith/wiki/Guidelines-for-test-plans#areas-of-interest-)
- [ ] Test plan has been peer reviewed by project stakeholders and other
QA members
- [ ] Manually tested functionality on DP
- [ ] We had an implementation alignment call with stakeholders post QA
Round 2
- [ ] Cypress test cases have been added and approved by SDET/manual QA
- [ ] Added `Test Plan Approved` label after Cypress tests were reviewed
- [ ] Added `Test Plan Approved` label after JUnit tests were reviewed
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **Style**
- Enhanced the Canvas layout to adjust its height dynamically according
to the layout system in use.
- **Tests**
- Introduced tests to validate the main container's overflow behavior in
mobile responsive scenarios.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
