HTML/CSS edits and fixes to my Shopify site template - made within 3 days

General information for the website: We are launching a new site template for ouir website but need minor amends made. Existing site at www.shrops-design.co.uk
Kind of development: Customization of existing website
Description of requirements/features: Hi there,

We are looking for some final edits to be made to our new Shopify template (bought off the shelf here: http://cleanthemes.co.uk/products/canopy). Edits have been made by a PPH developer, but there are a couple of quirks to fix, and a little additional functionality to add.

I am looking for these changes to be made within 3 working days as my previous developer was late in delivering the required changes.

*************************
ADDITIONAL FUNCTIONALITY
*************************
Our current site (www.shrops-design.co.uk) has a navigation menu that floats when the user scrolls down the page. When the users scrolls back to the top, the menu appears back in its place.

Our new template does not have this functionality and we'd like it added. Can the floating menu look the same at it does when fixed in the header, but with a cart and mail icon added to the right of the menu (like in the current template's floating menu), and a small version of our logo (https://cdn.shopify.com/s/files/1/0203/2258/t/45/assets/compact_logo.png?6066037746755280999) appearing on the left. The floating version of the menu might have to be made taller to accommodate the round logo.

Cart and mail icons are already part of the site template's assets (they are defined in the CSS as .icon-mail and .icon-cart).

This floating menu should only appear at wider resolutions, the site template has a really nice mobile menu already set-up.

*************************
FIXES
*************************

There are some minor bugs in the code added by my last PPH developer (all under 'ENTER YOUR CUSTOM CODE BELOW HERE' in the CSS file (towards the bottom). These fixes all relate to that code, because they aren't present in the clean install of the Shopify template.

There is some redundant code in there too - I asked the developer to create the same floating menu as above but this wasn't displaying well with the cart button so I have restored a 'clean' install of the page templates so some of this code is now redundant and can be removed

1. At smaller resolutions when the nav menu turns into an expandable 'burger' icon and the menu floats at the top of the page, when the burger icon is clicked to display the menu (which swipes in from the left), the floating menu jumps down a little creating a gap at the top. I have attached screenshots showing this - please could it be fixed so the floating menu doesn't have the gap above. It should work like this (clean template install example): http://elda-theme.myshopify.com/. See diag 1. The menu also jumps up from the slightly lower position when the browser window is made smaller

2. In our 'about us' pages have a side bar added, which is hidden on smaller resolutions. But, at some resolutions, the page content appears UNDER the bar, and at smaller mobile resolutions (when the side bar is hidden), the page content doesn't fill all of the screen space. Please fix these issues. See diag 2.

3. Linked to point 1 above, when the window width is reduced and the nav menu turns into the mobile version, the menu displays oddly for a second and/or while the window is being resized, then returns to how it should display. I have screen recorded this behaviour - see diag3. Can you fix whatever is causing this - the same behaviour is not present on the demo template: http://elda-theme.myshopify.com/.

4. Can you remove any of the redundant code from the 'ENTER YOUR CUSTOM CODE BELOW HERE' section of the CSS file.

That's it!

If things so well there are some more CSS enhancements I'd like as we enhance the site.

Thanks for looking. Shopify experience expected.
Extra notes: