@-webkit-keyframes ld {
  0%   { transform: rotate(0deg) scale(1); }
  50%  { transform: rotate(180deg) scale(1.1); }
  100% { transform: rotate(360deg) scale(1); }
}
@-moz-keyframes ld {
  0%   { transform: rotate(0deg) scale(1); }
  50%  { transform: rotate(180deg) scale(1.1); }
  100% { transform: rotate(360deg) scale(1); }
}
@-o-keyframes ld {
  0%   { transform: rotate(0deg) scale(1); }
  50%  { transform: rotate(180deg) scale(1.1); }
  100% { transform: rotate(360deg) scale(1); }
}
@keyframes ld {
  0%   { transform: rotate(0deg) scale(1); }
  50%  { transform: rotate(180deg) scale(1.1); }
  100% { transform: rotate(360deg) scale(1); }
}

.m-progress {
  position: relative;
  opacity: .8;
  color: transparent !important;
  text-shadow: none !important;
}

.m-progress:hover,
.m-progress:active,
.m-progress:focus {
  cursor: default;
  color: transparent;
  outline: none !important;
  box-shadow: none;
}

.m-progress:before {
  content: '';

  display: inline-block;

  position: absolute;
  background: transparent;
  border: 1px solid #fff;
  border-top-color: transparent;
  border-bottom-color: transparent;
  border-radius: 50%;

  box-sizing: border-box;

  top: 50%;
  left: 50%;
  margin-top: -12px;
  margin-left: -12px;

  width: 24px;
  height: 24px;

  -webkit-animation: ld 1s ease-in-out infinite;
  -moz-animation:    ld 1s ease-in-out infinite;
  -o-animation:      ld 1s ease-in-out infinite;
  animation:         ld 1s ease-in-out infinite;
}

.btn-default.m-progress:before {
  border-left-color: #333333;
  border-right-color: #333333;
}

.btn-lg.m-progress:before {
  margin-top: -16px;
  margin-left: -16px;

  width: 32px;
  height: 32px;
}

.btn-sm.m-progress:before {
  margin-top: -9px;
  margin-left: -9px;

  width: 18px;
  height: 18px;
}

.btn-xs.m-progress:before {
  margin-top: -7px;
  margin-left: -7px;

  width: 14px;
  height: 14px;
}