Poll untill styles are loaded

styleWaiter.js

var href = 'http://url.com'
appendStyle(href)    
waitForStyles(loadApp)

function appendStyle(href) {
  var link = document.createElement('link')
  link.setAttribute('rel', 'stylesheet')
  link.setAttribute('type', 'text/css')
  link.setAttribute('href', href)
  document.head.appendChild(link)
}

function waitForStyles(callback) {
  var interval = setInterval(findStyles, 50)

  function findStyles() {
    if (styleFound()) {
      clearInterval(interval)
      callback()
    }
  }
  
  function styleFound() {
    var styleSheets = document.styleSheets
    for (var i = 0, length = styleSheets.length; i < length; i++) {
      var styleHref = styleSheets[i].href
      if (styleHref && styleHref.indexOf(href)) return true
    }
    return false
  }  
}