【Sass】IE8以上対応の縦横中央揃え【Mixin】 ref: http://qiita.com/sawadays0118/items/b44c2082560242b74f74

_mixin.scss

// * Vartical & Horizontal Centering (IE8 and above. use :before.)
@mixin vh-center {
    text-align: center;
    &:before {
        content: "";
        display: inline-block;
        vertical-align: middle;
        height: 100%;
    }
    & > * {
        display: inline-block;
        vertical-align: middle;
    }
}

index.html

<div class="vhCenter"><img src="http://placeimg.com/200/200/any" alt=""></div>

test.css

.vhCenter { position: relative; width: 600px; height: 600px; background: #ccc; }
.vhCenter > * { position: absolute; top: 0; bottom: 0; margin-top: auto; margin-bottom: auto; }

test.scss

.vhCenter {
    @include vh-center(y);
    width: 600px;
    height: 600px;
    background: #ccc;
}