Untitled

<!DOCTYPE html>
<html>

<head>

</head>
<body>
    <div id="main">
    <button onclick="back()">WSTECZ</button>
    <button onclick="next()">DALEJ</button>
    <button id="button_kolor" onclick="red()">ZMIEN KOLOR</button>
    <p>Witam na mojej stronie</p>
    </div>
<script>
function back(){
    window.history.back();
}
function next(){
    window.history.forward();
}
function red()
{
document.bgColor='red'

}


var kolorek = "white"
function zmianakolor()
{
    if (kolorek == "white"){
        document.bgColor='black'
        document.getElementById("main").style.color = "White"
        kolorek = "black";
    }
    else if (kolorek == "black"){
        document.bgColor='white'
        document.getElementById("main").style.color = "black"
        kolorek = "yellow";
    }
    else if (kolorek == "yellow"){
        document.bgColor='yellow'
        document.getElementById("main").style.color = "black"
        kolorek = "white";
    }


}

</script>
    <button onclick="zmianakolor()">ZMIEN KOLOR</button>
</body>
</html>