How to Prevent Image Resizing In Real Time (during page load)

When I visit the homepage of my site, the header image at the top of the page loads at 90% width, and then expands to 100% width as the page continues to load. If you scroll down, it looks like all elements that are intended to be full-width, initially load at about 90% of their full width, and then go on to expand.

I am trying to locate where in the code this is happening. I thought it might be in the css style sheet but i'm not having any luck locating it. My best guess is there is some sort of wrapper loading before the image expands?

For more info, the image is being pulled in using the WPBakery Visual Composer plugin. I tried turning off the image parallax, which removed the image entirely.

I'm inspecting the source code, but nothing is jumping out to me (my webdev knowledge is extremely basic). I'm looking for any recommendations for where to look in the code.

I'm not sure what is causing the problem, but the source code can be viewed here: https://dev-nurseregistry.pantheonsite.io/

Solution

It seems like something from Javascript is loading after the initial page load. If you go to Google Chrome dev tools -> Sources -> Then (on the right side) choose Event Listener breakpoints and under DOM Mutation check DOMContentLoaded and reload the page, it will load DOM step by step. On the initial load elements have a bit different style - your div.site-inner is not full width.
When you are clicking that little blue play button on the screen, it goes on another step. After 4 or 5 steps the content goes full width. If you look into the network tab (also in the dev tools) you can see that widgets.js and platform.js were loaded and after those also some images. I'd say that you have to look in your js files for something you load after the initial page load.
When comparing loaded page and partially loaded side to side, it shows vc_section hide-mobile as display: block and vc_section hide-desktop as display: none.

Edit
Just read hungerstar's comment - he shows a bit more of the cause. I just found the result of that cause. Hope it helps.