Scope of #define preprocessor in C

The scope of #define is till the end of the file. But where does it start from?

Basically I tried the following code.

#include <stdio.h>
#include <stdlib.h>

#define pi 3.14

void fun();

int main()
{
    printf("%f \n", pi);
    #define pi 3.141516
    fun();
    return 0;
}

void fun()
{
    printf("%f \n", pi);
}

The output of the above program comes out to be

3.140000
3.141516

Considering preprocessing for main the value of pi should be 3.141516 and outside main 3.14. This is incorrect but please explain why.