username color change

[LethalJ]

Heya guys, hoping someone can help me with this. Basically we want to add two toned donator to forum as shown below.



I'm using the following code to achieve this

if( strpos( $user['musername'], 'tone: true;' ) !== false ) 
{ 
    $i = $b = 0; 
     
    $username = ''; 

    $colours = array('009B48','FF7900'); 

    while( $i < strlen( $user['username'] ) ) 
    { 
        if( $b > ( count( $colours ) - 1 ) ) $b = 0; 
         
        $username .= '<span style="color: #' . $colours[ $b ] . '">' . $user['username'][$i] . '</span>'; 
         
        ++$b; 
        ++$i; 
    } 
     
    $user['musername'] = '<strong>' . $username . '</strong>'; 
}

How could I seperate these colors eg Green first blending into the orange as shown below




Any help is greatly appreciated