Override body style for content in an iframe

user_771151 0
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How can I control the background image and colour of a body element within an iframe? Note, the embedded body element has a class, and the iframe is of a page that is part of my site.

The reason I need this is that my site has a black background assigned to the body, and then a white background assigned to divs that contain text. A WYSIWYG editor uses an iframe to embed content when editing, but it doesn't include the div, so the text is very hard to read.

The body of the iframe when in the editor has a class that isn't used anywhere else, so I'm assuming this was put there so problems like this could be solved. However, when I apply styles to class.body they don't override the styles applied to body. The weird thing is that the styles do appear in Firebug, so I've no idea what's going on!

Thanks

UPDATE - I've tried @mikeq's solution of adding a style to the class that is the body's class. This doesn't work when added to the main page's stylesheet, but it does work when added with Firebug. I'm assuming this is because Firebug is applied to all elements on the page whereas the CSS is not applied within iframes. Does this mean that adding the css after window load with JavaScript would work?

overriding iframe css styles
10 Answers

Override another domain iframe CSS

By using part of SimpleSam5's answer, I achieved this with a few of Tawk's chat iframes (their customization interface is fine but I needed further customizations).

In this particular iframe that shows up on mobile devices, I needed to hide the default icon and place one of my background images. I did the following:

Tawk_API.onLoad = function() {
// without a specific API, you may try a similar load function
// perhaps with a setTimeout to ensure the iframe's content is fully loaded
  $('#mtawkchat-minified-iframe-element').
    contents().find("head").append(
     $("<style type='text/css'>"+
       "#tawkchat-status-text-container {"+
         "background: url(https://example.net/img/my_mobile_bg.png) no-repeat center center blue;"+
         "background-size: 100%;"+
       "} "+
       "#tawkchat-status-icon {display:none} </style>")
   );
};

I do not own any Tawk's domain and this worked for me, thus you may do this even if it's not from the same parent domain (despite Jeremy Becker's comment on Sam's answer).

user_62258380

This should work with cross domain if you're the owner of the both

The trick here is to assign a global css variable to your body, to listen message with the new color, and then to change the global css variable once receive a message.

I'm using angular, but it should work with pure javascript

My use case was to show to the user what he how the color change would impact his website in the iframe before saving it

Domain A

@ViewChildren('iframeContainer') iframeContainer: QueryList<ElementRef>

sendDataToIframe(
  data = {
      type: 'colorChange',
      colors: {primary: '#000', secondary: '#fff'},
  },
): void {
  if (this.targetUrl)
    this.iframeContainer.first.nativeElement.contentWindow.postMessage(data) // You may use document.getElementById('iframeContainer') instead
}

Domain B

acceptedEditOrigins = [
  'https://my.origine.ccom', // Be sur to have a correct origin, to avoid xss injecto: https://en.wikipedia.org/wiki/Cross-site_scripting
]

constructor() {
// Listen to message
window.addEventListener('message', (event) => this.receiveMessage(event), false)
}

receiveMessage(event: MessageEvent) {
  if (this.acceptedEditOrigins.includes(event.origin))
    switch (event.data.type) {
      case 'colorChange': {
        this.setWebsiteConfigColor(event.data.colors)
      }
    }
}

setWebsiteConfigColor(colors: WebsiteConfigColors) {
  if (colors) {
    const root = document.documentElement
    for (const [key, value] of Object.entries(colors)) {
       root.style.setProperty(`--${key}`, value) // --primary: #000, --secondary: #fff
    }
  }
}


body {
  background-color: var(--primary);
}
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