Пишу программу "Змейку" и всё время такой серый фон,что делать?

program Shapoval;
uses crt, graph;
const N=50;
var
snake: array [1..N, 1..N] of integer;
i,lenght,ax,bx:integer;
apple_x,apple_y:integer;
ch:char;
answer:char;
out_of_programm:boolean;
Gd,Gm,Ge:integer;
x,y:integer;
procedure Init;
begin
  {init graphics with autodetection}
  Gd := Detect;
  InitGraph(Gd,Gm, '');
  end;
procedure renova;
  begin
    snake[1,1]:=12;
    snake[1,2]:=12;
     for i:=2 to N do
      begin
       snake[1,i]:=0;
       snake[1,i]:=0;
      end;
    lenght:=1;
    out_of_programm:=false;
    apple_x:=60;
    apple_y:=60;
    ch:=#77;
end;
 
 
procedure move;
begin
  if lenght>1 then
    begin
      for i:=0 to lenght-2 do
        begin
        snake[1,lenght-i]:=snake[1,lenght-i-1];
        snake[2,lenght-i]:=snake[2,lenght-i-1];
       end;
   end;
    case ch of
     #77: snake[1,1]:=snake[1,1]+6;
     #75: snake[1,1]:=snake[1,1]-6;
     #80: snake[2,1]:=snake[2,1]+6;
     #72: snake[2,1]:=snake[2,1]-6;
    end;
end;
 
 
procedure border_and_inter;
begin
if (snake[1,1]<=0) or (snake[1,1]>=720) then out_of_programm:=true;
for i:=3 to lenght do
begin
if (snake [1,1]=snake[1,i]) and (snake[2,1]=snake[2,i]) then
out_of_programm:=true;
end;
end;
 
 
procedure catch;
begin
   if (snake[1,1]=apple_x) and (snake[2,1]=apple_y) then
      begin
      apple_x:=(random(22)+9)*6;
      apple_y:=(random(22)+18)*6;
lenght:=lenght+1;
end;
end;
 
 
 
procedure picture;
begin
CLRSCR;
for i:=1 to lenght do circle(snake[1,i],snake[2,i],3);
circle(apple_x,apple_y,3);
end;
 
 
 
begin
 repeat
 Gd:=Detect;
  InitGraph(Gd,Gm,'');
  textcolor(blue);
    renova;
       repeat
        move;
        border_and_inter;
        catch;
        picture;
        delay(90);
        if KeyPressed then ch:=ReadKey   ;
       { if ch=#32 then out_of_programm:=true}
       until out_of_programm=true;
        ch:=ReadKey;
      until ch=#13;
      exit;
end.