加载样式文件

function loadStyle(url) {
  try {
    document.createStyleSheet(url);
  } catch (e) {
    var cssLink = document.createElement("link");
    cssLink.rel = "stylesheet";
    cssLink.type = "text/css";
    cssLink.href = url;
    var head = document.getElementsByTagName("head")[0];
    head.appendChild(cssLink);
  }
}