I’m in the process of creating a blog. While I am designing a completely custom theme, it will take some time to completely design and develop the theme. I noticed that the Casper theme is quite clean, and with some HTML/CSS modifications, it’ll work quite well until I can complete the work on my long term theme.
Few questions:
Is there a chance that I’ll be violating any usage rules by doing this?
What would be the best way to go about doing this without putting myself in a place to completely screw up my site if Ghost v2.5 drastically changes something that affects the design or functionality?
Absolutely not, Casper is designed specifically for this purpose and is MIT Licensed so you’re all good
Ghost follows semver so won’t introduce any breaking changes for themes until the next major release (3.0.0) and we tend not to have major releases too often - there was ~1year between 1.0.0 and 2.0.0
The worst that can happen within the 2.x series for theme compatibility is that a new feature is introduced that requires some additional CSS/JS or a bit of HTML to implement - the recent gallery feature in 2.1.0 is a good example Ghost Handlebars Themes - Building a custom Ghost theme - Docs