¿Cómo puedo evitar que copien el código de mi página web?

La respuesta sencilla es que no se puede, no se puede evitar que el código fuente de una página web, el código HTML,CSS y JavaScript, sea analizado y copiado por otra persona. Sí que existen algunas técnicas para ofuscar el código, para hacer que sea un poco más difícil de entender, pero no hay forma de ocultarlo.

En How do I stop somebody from viewing the source code of the webpage in browsers? han hecho la pregunta y la han contestado.

La respuesta más votada dice:

I would discourage you from trying to obfuscate HTML. Here’s why:

1. You won’t stop experienced web developers from copying your design if they want; it is not too hard to replicate the layout of a web page without the source code. (On the other hand, the functionality of a complicated website is much, much harder to replicate without the source code, so that’s a different story.)
2. Instead you’ll make it hard for beginners to learn. For example, suppose I were a beginner and I wanted to know how to make rectangles with rounded corners. There are a lot of these on Quora, so all I’d have to do is view the source of this page and see what HTML and CSS is being used to produce the rounded corners. If I couldn’t do that, it would be annoying, and Quora wouldn’t really benefit from preventing me from doing it.