var mode = -1
function inc(a) {
    if (mode != 1) {
        mode = 1
        document.getElementById('s2').style.display = 'block'
        document.getElementById('s1').style.display = 'none'
        a.style.backgroundColor = '#e1e1e1'
        document.getElementById('a1').style.backgroundColor = ''
        var speed = document.getElementsByTagName("EM")
        for (var i = 0; i < speed.length; i++)
            speed.item(i).innerHTML = speed.item(i).innerHTML * 1.5
    }
}
function dec(a) {
    if (mode != 2) {
        mode = 2
        document.getElementById('s2').style.display = 'none'
        document.getElementById('s1').style.display = 'block'
        a.style.backgroundColor = '#e1e1e1'
        document.getElementById('a2').style.backgroundColor = ''
        var speed = document.getElementsByTagName("EM")
        for (var i = 0; i < speed.length; i++)
            speed.item(i).innerHTML = speed.item(i).innerHTML / 1.5
    }
}
inc(document.getElementById('a2'))