Home page Content misaligned with Logo & Slideshow

Hi. Brilliant theme! One small problem I’ve been unable to solve (I’m a newbie): My site is https://petpaintings.co.nz/. On the static home page I have a header logo & Flex slider (logo and slides are both 1140px wide). In the page content area I have a poster image (also 1140px wide) followed by some text. However all the content I have entered via the Page Edit box is offset to the right by about 20px.

Due to the fact that the content of my WooCommerce Gallery, Video and Forum pages is correctly aligned with the same header logo, I assume the problem lies with my home page content. I have experimented with different alignments for the poster image, changed the default page template to Feature and Fullwidth – to no avail. It is as though the entire container for the page content is offset to the right by 20 pixels. Doubtless I’ve done something stupid, but any thoughts on how to correct very much appreciated.