Example of Theme

Musical theme:A fundamental musical motif or passage of music which defines the piece.
Literary theme: A subject or genre which is a descriptor of the nature of the work.
Design theme:A design element common to all aspects of the design and design methodology.
Party theme:A motif for party clothes and features.
Fashion theme: A general cultural orientation or look.
The word derives from the musical usage, but has been extrapolated across other concepts, which has expanded its use as an idiom considerably.

Examples of Themes:

Musical:Theme From A Summer Place
Literary: Bohemian storylines theme
Design: Urban chic theme
Party: 60s party theme
Fashion: Gothic fashion theme
https://acm.pku.edu.cn/JudgeOnline/problem?id=1743
https://www.sjsu.edu/faculty/patten/theme.html
https://en.wikipedia.org/wiki/Theme_(literature)
https://en.wikipedia.org/wiki/Theme_(music)

Image Example of Theme:

Stealth's ride theming at thorpe park

Oakwood theme park: Vertigo