Hamburger menu not working on mobile

[jacob-g]

Reported by ahmetlii

Steps to reproduce:

1. Open the Wiki on a mobile browser (I used Firefox Android)
2. Click the hamburger menu at the top left

Expected behavior: sidebar opens Actual behavior: sidebar does not open (nothing happens)

[Kenny2github]

Cannot reproduce on Chrome mobile so this seems to be browser-specific.

[jacob-g]

I am getting the following console error:

Uncaught TypeError: sidebarToggle.computedStyleMap is not a function

Relevant code:

var sidebarToggle = document.querySelector('#navigation .sidebar-toggle')
sidebarToggle.addEventListener('click', function(){
    if (sidebarToggle.computedStyleMap().get('display').value === 'none') return; // this is the line that fails
    if (!sidebarShown) {
        document.querySelector('#view .inner .left').style.left = '0';
    } else {
        document.querySelector('#view .inner .left').style.left = null;
    }
    sidebarShown = !sidebarShown;
});

[jacob-g]

From MDN: https://developer.mozilla.org/en-US/docs/Web/API/Element/computedStyleMap computedStyleMap is not compatible with Firefox