Tweaking a muse website so it works on desktop and mobile

Hi,

I have designed a website in Muse, it's my first thing I've ever done in it for a friends company. He really liked it and wanted me to continue with it so I did, however, there's certain bits I just can't do and time has run away and it's a bit embarasssing to be honest! So I thought, bite the bullet and ask for a bit of help.

So, what I have is a very simple one page parallax site, in sections. I've published it so hopefully the below text is a bit clearer!

http://sixtythree.businesscatalyst.com/index.html

So here comes the incoherent blurb-brief about what needs fixing!

Home:
A large background image and main navigation. This section has two issues, 1, I cna't get the background image to always work at 100% no matter what screen size, 2, The anchor links depsite me adding 'overflow-x:hidden;' still seem to have a small amount of horizontal movement when clicked. On my larger monitor it seems ok but on my 13 inch macbook it moves a bit on x-axis.

Portfoilio:
This is a section of thumbnails which open in lightbox, this section is what I'm having the most problems with,
Firstly, the thumbnails part, they all look fine and are spaced right more or less, but some of the triggers are too big, yet when I go into design mode I can't make the trigger smaller it bounces back to the original size annoyingly. Some buttons are ok, but for example, if you click on the 'C' in Digital Canvas it takes you to the below button's destination 'set design'. I think it should be quite easy to fix for someone who's used Muse a bit but I just can't figure it out!

Secondly is what happens when the thumbs are clicked, each thumbnail opens a lightbox with a title, paragraph of text, close button and image or video depending. The issue with this is some of the boxes don't seem to let me drag images into and also the size of the lightbox when looked at on a mobile is too wide for the screen yet if i try and shrink it and say put the title above the image or video then have the paragraph beneath it it wont let me resize the box on the x axis, it bounces back to it's original size. Again, as I'm so new to it, I'm unsure if it's me being a total noob and easy to fix or not.

Clients:
This section works fine it just has that slight anchor link issue mentioned before when clicked on smaller screens.

Contact:
This section works fine but I think Google maps should go beneath the contact info because when scrolling over the map it starts zooming. I could fix that easy enough it's the other probs above which are doing my brain in :)

That's it, as I said it's my first project so I kept it simple. I'd be happy for you to check it on mobile and tablet and see if there are any other tweaks that need doing too. Most of it seems fine it's just the portfolio lightboxes on mobile which are a mess. As I said time is of the essence a bit here so I'd appreciate a quick reply with a rough estimate of time to fix it all and do a responsive/adaptive check. I'd happily pay you per hour or a fixed rate depending on what you think time wise. I think for someone who knows this goddamn program properly it should be an easy win. I would of course send you all the files etc via wetransfer so you could work on it all or it would be impossible haha.

Anyway, hope you can help,

Eugene