Fix side menu bar issues

I have build a website for a client using Word Press the website address is [login to view URL] I am using a theme provided by a company called Ink Themes I have emailed them to fix issues with the website and how it displays on different devices yet every time they say they have fixed the issue on one devices it stuffs it up on another see below what the issue is: 1. The sidebar on a computer juts out over the image see screen shot attached to project titled (side bar computer error). 2. On a mobile device the side bar is not meant to show at all it is meant to have a little icon people can click on to display the sidebar when clicked on. If I access the site on my HUAWEI mobile phone it works as it should see attachment (HAUWEI phone correct sidebar layout) but on an Iphone and I presume and ipad (I have not checked on Ipad) it does not display properly as it shows about 15% of the side menu that should not be displayed at all see screenshot attached (Iphone side bar error). I need the issue fixed so the sidebar displays correct width on all computer screens i.e. it will resize for smaller screens and larger so on. I need on the iphone and Ipad that the sidemenu not show at all and display like it does with on the HUAWEI phone with just the icon in the top left. I need this completed within the next hour time I know it is CSS I just dont have skill set to complete.