var Browser = {
    Version: function() {
        var version = 999;
        if (navigator.appVersion.indexOf("MSIE") != -1)
            version = parseFloat(navigator.appVersion.split("MSIE")[1]); 
        return version;
    }
}

function resizeP() {
    var width = document.getElementById("middle").offsetWidth;
    if (Browser.Version() == 8) {
        document.getElementById("right_m").style.width = width / 2 + 10 + "px";
        document.getElementById("left_m").style.width = width / 2 - 30 + "px";
    } else {
        document.getElementById("right_m").style.width = "49%";
        document.getElementById("left_m").style.width = "49%";
    }
}

if (Browser.Version() == 8) {   
    window.onresize = resizeP;
}

window.onload = resizeP;