Reply To: Animation behaving odd in FX when elements hit its containers boundaries.

[paulob]

You could also fix it by extending the area outside the viewport for the pulse element.

.pulse {
    border-radius:100%;
    border:4px solid rgba(255,255,255,.5);
    width:100px;
    height:100px;
    opacity:0;
    margin: auto;
    position: absolute;
    top: -99em;
    left: -99em;
    bottom: -99em;
    right: -99em;
    z-index:0;
}