//----------------- HTML
<div class="wrapper-12">
	<div id="spinner12" class="border-circle"></div>
</div>

//----------------- CSS
.wrapper-12{
	display:flex;
    justify-content: center;
	width:50px;
	height:50px;
	margin:10px;
	background: linear-gradient(35deg, rgba(112, 175, 4, 1) 0%, rgba(0, 75, 64, 1) 50%, rgba(32, 167, 77, 1) 100%);
	border-radius:50%;
	animation: spinn_twelfe 3s infinite;
	animation-timing-function: linear;
}

.border-circle{
	width:45px;
	height:45px;
	border-radius:50%;
	background-color:black;
	margin:auto;
}

@keyframes spinn_twelfe {
	0%{
		transform: rotate(0deg);
	}
	50%{
		transform: rotate(-600deg);
	}
	100%{
		transform: rotate(360deg);
	}
}