Anchor links work and positioning takes place but landing is hidden by site header

Hello, I'm using anchor links as described here: 

https://support.squarespace.com/hc/en-us/articles/207135178-Creating-anchor-links

They appear to work but the landing text is not visible. It appears to me that the page jump works and is probably positioned the landing text at the very top of the browser window but the site header hides the landing text. The result is that the landing text is not seen and the visitor ends up looking at page content that is several lines down from where I want it to be. How can I have these jumps account for the size of the site header and have the landing text appear just under the site header?

Thanks