Try it Live

<!DOCTYPE html>
<html>
  <head>
   <style>
    #blackbg {
      background-color:black;
    }
    
    #whitebg {
      background-color:white;
    }
    
    #red {
      color:rgb(255,0,0);
    }
    
    #green {
      color:rgb(0,255,0);
    }
    
    #blue {
      color:rgb(0,0,255);
    }
    
    #cyan {
      color:rgb(0,255,255);
    }
    
    #yellow {
      color:rgb(255,255,0);
    }
    
    #pink {
      color:rgb(255,0,255);
    }
    
    #white {
      color:rgb(255,255,255);
    }
    
    #black {
      color:rgb(0,0,0);
    }
   </style>
  </head>
<body>
<div id="blackbg">
  <p id="red">Red text color is rgb(255,0,0)</p>
  <p id="green">Green text color is rgb(0,255,0)</p>
  <p id="blue">Blue text color is rgb(0,0,255)</p>
  <p id="cyan">Cyan text color is rgb(0,255,255)</p>
  <p id="yellow">Yellow text color is rgb(255,255,0)</p>
  <p id="pink">Pink text color is rgb(255,0,255)</p>
  <p id="white">White text color is rgb(255,255,255)</p>
</div>

<div id="whitebg">
  <p id="black">Black text color is rgb(0,0,0)</p>
</div>

</body>
</html>