.scaling-svg-container {
    display: inline-block;
    position: relative;
    width: 50%;
    padding-bottom: 20%; /* depends on svg ratio, for my zebra height/width = 1.2 so padding-bottom = 50% * 1.2 = 60% */
    vertical-align: middle; /* top | middle | bottom ... do what you want */
}
.scaling-svg {
    display: block;
    position: absolute;
    top: 50%;
    left: 50%;
}