Upgrade website from Joomla! 3.x to Joomla! 4.x, by keeping the same look and feel

I am looking for a skilled Joomla! developer to upgrade my website from Joomla! 3.x to Joomla! 4.x while keeping the same look and feel.

Requirements:
- Experience in upgrading Joomla! websites
- Expertise in Joomla! 4.x
- Ability to ensure the website maintains the current look and feel throughout the upgrade process

Additional Information:
- I have a backup of my current website
- There are no additional features or changes to implement beyond the upgrade
- There are no specific extensions or plugins that need to be maintained
- I would prefer not using Page Builder but sticking to the proprietary Joomla! plugins
- I would like to maintain the same visual effects
- The website should be responsive, as it is now