There you go:
Use:
document.body.style.zoom=1.0;this.blur();
1.0 means 100%
150% would be 1.5
1000% would be 10.0
this.blur() means that the curser, maybe you selected an input field, looses focus of every select item.
or:
You can use the css3 element zoom (Source)
Firefox does not allow zooming with the browser because you can't access the user properties via javascript or sth.
So you can just use some CSS styles which allow to zoom (CSS3: zoom, as mentioned above) or to increase the text size! Which you could do with including a different CSS file for example. But here you have the "jumpy" problem, because the styled css elements (floated etc.) have to "interact" different in fact of their attributes.
The zoom I posted above works well in Chrome and IE8+ (FF not supported as mentioned)
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Additional information:
Here is an example on how to zoom exactly with the zoom option.
Example application can be found here
The zoom option normally handles the zoom as your browser does!
But this is still all stuff, which is not supported by Firefox, or maybe Safari & Opera? In chrome and IE it works!
Another solution would be: Place your main sizes in "em", and then work around by setting sizes like 100%, 110% (all over the css). So you could have differen CSS files, and "just" need to replace the % attributes!
Yet I don't think there might be other solutions! :(
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