if (document.images) {  
      var button1_up = new Image();
      button1_up.src = 'i/domu.jpg';  
      var button1_over = new Image();
      button1_over.src = 'i/domuOver.jpg';
      var button2_up = new Image();
      button2_up.src = 'i/pokryti.jpg';  
      var button2_over = new Image();
      button2_over.src = 'i/pokrytiOver.jpg';
      var button3_up = new Image();
      button3_up.src = 'i/pripojeni.jpg';  
      var button3_over = new Image();
      button3_over.src = 'i/pripojeniOver.jpg';
      var button4_up = new Image();
      button4_up.src = 'i/cenik.jpg';  
      var button4_over = new Image();
      button4_over.src = 'i/cenikOver.jpg';
      var button5_up = new Image();
      button5_up.src = 'i/podpora.jpg';  
      var button5_over = new Image();
      button5_over.src = 'i/podporaOver.jpg';
      var button6_up = new Image();
      button6_up.src = 'i/kontakt.jpg';  
      var button6_over = new Image();
      button6_over.src = 'i/kontaktOver.jpg';
    } 
  function over_button() {
    if (document.images) {
      document["buttonOne"].src = button1_over.src
    }
  }   
  function up_button() {
    if (document.images) {
      document["buttonOne"].src = button1_up.src
    }
  }  
  function over_button2() {
    if (document.images) {
      document["buttonTwo"].src = button2_over.src
    }
  }   
  function up_button2() {
    if (document.images) {
      document["buttonTwo"].src = button2_up.src
    }
  } 
  function over_button3() {
    if (document.images) {
      document["buttonThree"].src = button3_over.src
    }
  }   
  function up_button3() {
    if (document.images) {
      document["buttonThree"].src = button3_up.src
    }
  }
  function over_button4() {
    if (document.images) {
      document["buttonFour"].src = button4_over.src
    }
  }   
  function up_button4() {
    if (document.images) {
      document["buttonFour"].src = button4_up.src
    }
  }
  function over_button5() {
    if (document.images) {
      document["buttonFive"].src = button5_over.src
    }
  }   
  function up_button5() {
    if (document.images) {
      document["buttonFive"].src = button5_up.src
    }
  }
  function over_button6() {
    if (document.images) {
      document["buttonSix"].src = button6_over.src
    }
  }   
  function up_button6() {
    if (document.images) {
      document["buttonSix"].src = button6_up.src
    }
  }