文字變大函式

//將文字變大的函式組
function fonts(idbum) {
    document.getElementById(idbum).style.fontSize = "21px";
    document.getElementById(idbum).style.textIndent = "30px";
    document.getElementById(idbum).style.fontWeight = "bold";
    xia1 = idbum.substring(2)
    numi = xia1
    var div = document.getElementById("audio-body").getElementsByTagName("div");
    for (var i = 0; i < div.length; i++) {
        if (idbum != div[i].id) {
            div[i].style.fontSize = "16px";
            div[i].style.textIndent = "20px";
            bgc();
        }
    }
}