.ingroup  { position: relative; }
.ingroup .form-control { text-align: center; }

.ingroup-prepend, 
.ingroup-append { display: inline-block; position: absolute; top: 0; height: 100%; }

.ingroup-prepend {  left: 0;}
.ingroup-append { right: 0;  }

.btn-spinner {
    display: block; width: 40px; height: 100%;
    border:1px solid transparent;
	background-color: transparent; 
    background-repeat: no-repeat;
    background-position: center center; /* fixed*/ 
    background-size: 16px 16px;
}

.btn-decrement { background-image: url('../images/spinner-minus.svg'); }
.btn-increment { background-image: url('../images/spinner-plus.svg'); }