SCSS + COMPASS: animated intro

#presentation {
    color: #fff;
    text-shadow: 0 0 10px #fff;

    a {
        text-shadow: 0 !important;
        color: #fff;
    }

    .background {
        position: fixed;
        background-color: #222;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        z-index:999;
        @include animation-delay(9s);
        @include animation-duration(2.5s);
        @include animation-iteration-count(1);
        @include animation-fill-mode(both);
        @include animation-name(last);
    }

    > div {
        position: absolute;
        top: 50%;
        left: 10%;
        right: 10%;
        text-align: center;
        z-index: 999;
        font-size: 40px;

        &.first {
            @include animation-delay(1s);
            @include animation-duration(2.5s);
            @include animation-iteration-count(1);
            @include animation-fill-mode(both);
            @include animation-name(scale);
        }
        &.second {
            @include animation-delay(3s);
            @include animation-duration(2.5s);
            @include animation-iteration-count(1);
            @include animation-fill-mode(both);
            @include animation-name(scale);
        }
        &.third {
            @include animation-delay(5s);
            @include animation-duration(2.5s);
            @include animation-iteration-count(1);
            @include animation-fill-mode(both);
            @include animation-name(scale);
        }
        &.fourth {
            @include animation-delay(7s);
            @include animation-duration(2.5s);
            @include animation-iteration-count(1);
            @include animation-fill-mode(both);
            @include animation-name(scale);
        }
    }
}
@include keyframes(scale) {
    0% { transform: scale(0); }
    10% { transform: scale(1.2); }
    20% { transform: scale(1); }
    70% { transform: scale(1.2); }
    100% { transform: scale(0); }
}
@include keyframes(last) {
    0% { opacity: 1; }
    10% { transform: scaleY(0); }
    100% { opacity: 0; transform: scaleY(0); }
}