iOS系统禁止微信客户端修改字体大小：
body {
-webkit-text-size-adjust: 100% !important;
text-size-adjust: 100% !important;
-moz-text-size-adjust: 100% !important;
}
Android 则通过js 调整：
<script>
(function () {
if (typeof WeixinJSBridge == "object" && typeof WeixinJSBridge.invoke == "function") {
handleFontSize();
} else {
if (document.addEventListener) {
document.addEventListener("WeixinJSBridgeReady", handleFontSize, false);
} else if (document.attachEvent) {
document.attachEvent("WeixinJSBridgeReady", handleFontSize);
document.attachEvent("onWeixinJSBridgeReady", handleFontSize);
}
}
function handleFontSize() {
WeixinJSBridge.invoke('setFontSizeCallback', { 'fontSize': 0 });
WeixinJSBridge.on('menu:setfont', function () {
WeixinJSBridge.invoke('setFontSizeCallback', { 'fontSize': 0 });
});
}
})();
</script>
