I recently did an extensive test of many, many HTML templates.
The key thing I looked for was when the templates had been created and how often/how recently it had been updated - sites like Envato are loaded to the brim with old no-longer-updated templates.
I tested by loading them on the iPhone 6.
In almost every single case, the layout instantly broke, OR the side menu didn't work, OR the side menu felt "sticky" and would not smooth scroll, OR sliding the side menu scrolled the underlying page as well.
That was 90% of the templates or more - the quality level in general is terrible.
The key thing I looked for was when the templates had been created and how often/how recently it had been updated - sites like Envato are loaded to the brim with old no-longer-updated templates.
I tested by loading them on the iPhone 6.
In almost every single case, the layout instantly broke, OR the side menu didn't work, OR the side menu felt "sticky" and would not smooth scroll, OR sliding the side menu scrolled the underlying page as well.
That was 90% of the templates or more - the quality level in general is terrible.
The ones we chose were from https://bootlab.io/themes - very nice quality.