Scale SVG sprite

HTML

<span class="icon_method1"></span>

<span class="icon_method1" style="font-size:2em;"></span>

<br/>
<span class="icon_method2 scale_1"></span>

<span class="icon_method2 scale_2"></span>

CSS

span {
    display:inline-block;
}
.icon_method1 {
    background: url('data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIzMiIgaGVpZ2h0PSIzMiIgdmlld0JveD0iMCAwIDMyIDMyIj4gPGNpcmNsZSBmaWxsPSJibHVlIiBjeD0iOCIgY3k9IjgiIHI9IjgiLz4gPGNpcmNsZSBmaWxsPSJyZWQiIGN4PSIyNCIgY3k9IjgiIHI9IjgiLz4gPGNpcmNsZSBmaWxsPSJ5ZWxsb3ciIGN4PSI4IiBjeT0iMjQiIHI9IjgiLz4gPGNpcmNsZSBmaWxsPSJncmVlbiIgY3g9IjI0IiBjeT0iMjQiIHI9IjgiLz4gPC9zdmc+') 100% 0;
    width:1.5em;
    height:1em;
    background-size:2em 2em;
}
.icon_method2 {
    background: url('data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIzMiIgaGVpZ2h0PSIzMiIgdmlld0JveD0iMCAwIDMyIDMyIj4gPGNpcmNsZSBmaWxsPSJibHVlIiBjeD0iOCIgY3k9IjgiIHI9IjgiLz4gPGNpcmNsZSBmaWxsPSJyZWQiIGN4PSIyNCIgY3k9IjgiIHI9IjgiLz4gPGNpcmNsZSBmaWxsPSJ5ZWxsb3ciIGN4PSI4IiBjeT0iMjQiIHI9IjgiLz4gPGNpcmNsZSBmaWxsPSJncmVlbiIgY3g9IjI0IiBjeT0iMjQiIHI9IjgiLz4gPC9zdmc+') 0 0;
}
.scale_1 {
    background-size:32px 32px;
    width:16px;
    height:16px;
}
.scale_2 {
    background-size:64px 64px;
    width:32px;
    height:32px;
}