Need help by generating a random number in an while loop for Arduino | Arduino | Forum

the program should generate a random color and stay that way. I know that it is not that hard but i really want to know why this isn't working.

I don't know why, but when i set a fix number like 100 the connected LED is bright. But when i try it with random numbers it is dark every time i restart the Arduino.

her is the code.

int mode;
const int led_red = 9;
const int led_green = 10;
const int led_blue = 11;
void setup() {
// put your setup code here, to run once:
pinMode(led_red,OUTPUT);
pinMode(led_green,OUTPUT);
pinMode(led_blue,OUTPUT);
randomSeed(analogRead(A0));
mode = 0;
}

void loop() {
// put your main code here, to run repeatedly:
int random_red;
int random_green;
int random_blue;
while(mode=0){
random_red = random(256); //Here is the problem. by a fix number like 100 it works but not a random number
random_green = random(256);
random_blue = random(255);
mode = 1;
}
while(mode=1){
analogWrite(led_red, random_red);
analogWrite(led_green, random_green);
analogWrite(led_blue, random_blue);
}
}

thx for your help.