Hi, I have some practical work experience in Grav CMS. Last year I got a chance to develop a website for a local photo studio in my city for which I chose Grav CMS.
I'm a web developer not a web designer, so I can't help you with design aspects of your website but as you've already mentioned in your project description that you have templates which I can use to develop your website. I don't have much experience in Twig but I can learn it quickly.
About me
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I'm a Software Developer. I have experience in modern web technologies including HTML5, CSS3, JavaScript, XML, JSON, AJAX, PHP, and MySQL. I also have experience in building command-line tools and utilities in PHP including web scrapers, web crawlers, and webbots.
If you would like to discuss your project with me then feel free to send me a message even when I'm offline. I do my best to reply within a few minutes when online and within a few hours when offline.