Hello @Creativecure,
I have tested your site site both in desktop (smaller browser size) and on my Android phone. The mobile menu closed after you hit the menu items. You may be having some caching issue. I am seeing that you are hosted in SiteGround. Could you please clear your site cache or at least disable the Supercacher in your hosting panel? The SuperCacher is developed by SiteGround exclusively for their customers. It increases the number of hits a site can handle and boosts the website loading speed. The SuperCacher includes 4 different caching options for maximum optimization of your websites. You can access the tool by clicking on the SuperCacher icon in your cPanel.
For more information about this, please check it out here: https://www.siteground.com/tutorials/supercacher/supercacher_intro.htm
And then please clear your browser cache (also in your client’s browser) or at least use the private browsing mode and test the site again.
Hope this helps. Kindly let us know how it goes.