Template:SpoilerBox

Usage: {{SpoilerBox|This text will be hidden.}}

Result:

Spoiler warning! This section reveals details about the story of Baldur's Gate 3.

This text will be hidden.

If you don't want the gradient use nograd:

Usage: {{SpoilerBox|nograd|This text will be hidden.}}

Result:

Spoiler warning! This section reveals details about the story of Baldur's Gate 3.

nograd