Thank you for the clarification.
In this case, I'd recommend using the Page Class option in the Joomla Menu Item settings instead of relying on the template style ID.
You can assign a unique class (for example, style-one or style-two) in Menus → Your Menu Item → Page Display → Page Class. Joomla will automatically add that class to the page's <body> element, allowing you to target it in your custom.css, for example:
.style-one .your-element {
/* Custom styles */
}
.style-two .your-element {
/* Custom styles */
}
This approach is more flexible, easier to maintain, and avoids depending on the active template style ID.