fb-login-button makes page jump up and down until it loads
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I added Facebook login to one of my websites. However, until the Facebook button switches from text to an actual fb-login-button, my site's height is larger than it should be and once the facebook button shows up, it goes back to normal. Does anyone know why that is? Should I modify anything? Here's the code for it:

    <div class="fb-login-button" style="float: left; overflow:hidden;" size="large" scope="user_about_me, email">Use Facebook Account to Login</div>