开启app的第一屏广告不是全面屏

操作系统:Android 8.1.0 (MI 8 Xiaomi/OPM1.171019.026/App6.31/v20006310)

WebView:Mozilla/5.0 (Linux; Android 8.1.0; MI 8 Build/OPM1.171019.026; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/62.0.3202.84 Mobile Safari/537.36