Wrong URL for banner-logo.svg in Safari

[wilkinsona]

For example, the Spring Boot docs are trying to load https://docs.spring.io/spring-boot/docs/2.5.0-SNAPSHOT/reference/img/banner-logo.svg. The correct URL is https://docs.spring.io/spring-boot/docs/2.5.0-SNAPSHOT/reference/htmlsingle/img/banner-logo.svg. This looks like a subset of #11.

[philwebb]

Safari is particularly annoying. It seems you can't have any variables in the property value, even if the image isn't a variable itself. Extracting the property seems to have fixed it.