.btn[class*=btn-icon] {
  position: relative;
}
.btn.btn-icon-left {
  padding-left: 40px;
}
.btn.btn-icon-left svg {
  left: 16px;
}
.btn.btn-icon-right {
  padding-right: 40px;
}
.btn.btn-icon-right svg {
  right: 16px;
}
.btn svg {
  position: absolute;
  width: 20px;
  height: 20px;
  transform: translateY(-50%);
  top: 50%;
}