Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

procedure TForm1.Button1Click(Sender: TObject);
 begin
   //75% of original size 
  WebBrowser1.OleObject.Document.Body.Style.Zoom := 0.75;
 end;

 procedure TForm1.Button2Click(Sender: TObject);
 begin
   //original size 
  WebBrowser1.OleObject.Document.Body.Style.Zoom := 1;
 end;

 {A page must be already loaded into TWebBrowser}
 {Eine Seite muss bereits in TWebBrowser geladen sein}

 //.zoom:=0.25; //25% 
//.zoom:=0.5; //50% 
//.zoom:=1.5; //100% 
//.zoom:=2.0; //200% 
//.zoom:=5.0; //500% 
//.zoom:=10.0; //1000% 

{----------}

 uses
   OleCtrls, SHDocVw;

 { 
Suppose That you want to use for buttons to give you the zooming 
(text size) options of MSIE, 
Button1 for smallest, Button2 for small, Button3 for medium, 
Button4 for large and Button5 for Largest, 
You have to set the value of the tag property for each button as following: 
 0: for the smallest text size, 
 1: for the small, 
 2: for medium, 
 3: for large, 
 4: for the largest. 

}


 procedure TForm1.Button1Click(Sender: TObject);
 var
   ZoomFac: OLEVariant;
 begin
   ZoomFac := TButton(Sender).Tag;
   WebBrowser1.ExecWB(OLECMDID_ZOOM, OLECMDEXECOPT_PROMPTUSER, ZoomFac);
 end;