Ghost/core/client/assets/sass/modules/animations.scss

//
// Animations
// --------------------------------------------------

@-webkit-keyframes off-canvas {
    0%   { left:0; }
    100% { left:300px; }
}
@-moz-keyframes off-canvas {
    0%   { opacity: 0; }
    100% { opacity: 1; }
}
@-o-keyframes off-canvas {
    0%   { opacity: 0; }
    100% { opacity: 1; }
}
@keyframes off-canvas {
    0%   { opacity: 0; }
    100% { opacity: 1; }
}

@include keyframes(fadeIn) {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}