BOUTON

    <script>
        var cpt=1;
        function bo() {
        cpt=cpt+1;
        console.log(cpt);
        if (cpt>1)
        {
            console.log("changement de theme")
            swapStyleSheet('css/PageCss2.css')
            document.getElementById('logo').setAttribute('src', 'jour.jpg');
            console.log(cpt)
            cpt=0


        }
        else
        {
            swapStyleSheet('css/page.css')
            document.getElementById('logo').setAttribute('src', 'nuit.jpg');
        }
        }
</script>
        <button id="bouton" onclick="bo()"><img src="nuit.jpg" id="logo"/></button>