function active_first() {          
  document.getElementById("pic_reckonstrukce").src = "grafika/home_menu_1_p.jpg";
}  
function deactive_first() {          
  document.getElementById("pic_reckonstrukce").src = "grafika/home_menu_1.jpg";
}
function active_second() {          
  document.getElementById("pic_bytove").src = "grafika/home_menu_2_p.jpg";
}  
function deactive_second() {          
  document.getElementById("pic_bytove").src = "grafika/home_menu_2.jpg";
}         
function active_third() {          
  document.getElementById("pic_sluzby").src = "grafika/home_menu_3_p.jpg";
}  
function deactive_third() {          
  document.getElementById("pic_sluzby").src = "grafika/home_menu_3.jpg";
}
function active_fourth() {          
  document.getElementById("pic_aktualni").src = "grafika/home_menu_4_p.jpg";
}  
function deactive_fourth() {          
  document.getElementById("pic_aktualni").src = "grafika/home_menu_4.jpg";
}

img1 = new Image();
img1.src = '../grafika/h1_menu_under_p.jpg';
img2 = new Image();
img2.src = '../grafika/h2_menu_under_p.jpg';
img3 = new Image();
img3.src = '../grafika/h3_menu_under_p.jpg';
img4 = new Image();
img4.src = '../grafika/h4_menu_under_p.jpg';
img5 = new Image();
img5.src = '../grafika/h5_menu_under_p.jpg';